Numbers in [brackets] are the mitzva-count according to the Sefer HaChinuch. Other counts vary.
G-d once again (previously with Frogs and "Dever") sends Moshe to Par'o (in his palace) to warn about the Locust.
[SDT] The signature of this week's sedra - BO EL PAR'O is a phrase that occurs three times, each as an introduction to one of the Plagues. Specifically, G-d said to Moshe to "come before Par'o" for the middle plague of each 3-plague set - FROGS, DEVER (animal disease), LOCUST. Baal HaTurim points out that when G-d sends Moshe to the royal palace, He uses the term BO. When He sends him to the river to find Par'o there, He uses the term LEICH.
This time, however, it is with the additional statement that G-d has hardened Par'o's heart so that His wonders will be evident to all, and that all will know Him. Moshe and Aharon warn Par'o of the potential devastation (the description of which is longer than usual).
Par'o's servants (advisors?) pressure Par'o into agreeing to release the People. Par'o offers Moshe the adults. Moshe's reply (which becomes a Jewish hallmark for the ages) is that our religious experiences must include ALL Jews, young and old. (Judaism places a premium on Chinuch.) The continuity of Judaism depends upon the relationship of one generation to the next. Par'o rejects this (as have other adversaries throughout our history) and expels Moshe and Aaron from his presence.
Locust were sent by G-d to punish Egypt by devouring the produce of the land. This was "measure for measure" punishment for the excessive field and planting work that Par'o imposed on the People of Israel in order to demoralize them and to prevent them from having a normal family life.
[Here's a Thought] Commentaries point out that Par'o and the Egyptians continually "overdid" their oppression and enslavement of the Jews. Even if we were to suggest that punishment is unfair to those who were acting according to G-d's wishes, it is for the excesses that they are being held strictly accountable. "Yes, I told you to rough them up, but I never said anything about beating them so mercilessly." (This does not mean to suggest that people who "play a part in G-d's plans" are not held accountable for their "regular" actions. They are. But there is special emphasis on the excesses. Having the people slave at making bricks is one thing. Withholding straw for the purpose is excessively cruel. Etc.)
On the other hand, the excessive cruelty of the Egyptians is partially responsible, so to speak, for G-d's switching to His Midat HaRachamim in judging the people, from the Midat HaDin which might have kept us in Egypt longer. The original prophecy to Avraham Avinu called for 400 years. Actual time spent in Egypt (not even in slavery) was "only" 210 years. The inclusion of the years from Yitzchak's birth is (can be seen as) a result of the excessive harshness of the Egyptian experience.
G-d tells Moshe to raise his hands over the land. Moshe raises his staff and the locust come. So overwhelming is this plague that Par'o "hurries" to call for Moshe and Aharon, admits to them that he has sinned, and asks them to pray for the removal of this terrible plague. Moshe does so, and a "reverse" wind causes the locust to disappear completely. G-d once again hardens Par'o's heart.
Plague #9 (just like #3-Lice and #6- Boils) is brought without warning.
The thrice repeated pattern is (1) find Par'o at the Nile and deliver the warning, (2) go to his palace and bring the warning "closer to home", and (3) twice-warned is sufficient; he won't let the People go, bring the next plague without additional warning. Additionally, there is an escalation in severity from the first to the second to the third plague in each set of three plagues.
Darkness, an unusual tangible darkness (not merely the absence of light), descends upon the Egyptians for a paralyzing 3 days (Rashi indicates that it was of a duration of six days). In the Jewish neighborhoods, there is light.
[Here's another thought] If darkness is usually considered to be the absence of light, then that can be the definition of "natural" darkness. Consistent with the other Makot, the plague of Darkness was not natural. Some of the unnatural qualities of the Darkness of Egypt was that it was substantive, that lighting a fire would not dispel it. This was a supernatural darkness. Perhaps, a darkness like pre-Creation darkness.
[SDT] "Man did not see his fellow, nor did a person rise from his place..." The Chidushei HaRim writes that this is a description of the worse kind of darkness in human life, when a person does not see the suffering of his fellow. Not only does he not extend his hand to help the other, but the ultimate result is the inability of the individual to even help himself. The People of Israel had light throughout their dwellings. May we always be able to see the plight of our fellow Jews and respond with acts of Chesed worthy of our Heritage.
Par'o calls for Moshe and tells him to go, even with the children, but to leave the livestock behind. Moshe insists that ALL will leave.
[SDT] Moshe's words to Par'o are: "We will also take our animals with us, for from them we will take to serve G-d." The plain understanding of the pasuk is that Moshe was referring to korbanot, sacrifices. The Malbim has another beautiful interpretation of Moshe's statement to Par'o. "From the animals we will take lessons in how to serve G-d - from the cat we will learn modesty, from the doves fidelity, from the ants industry and honesty, etc." Had we not received the Torah, which teaches us proper conduct, we would learn these lessons from our animals. (And even with the Torah to teach us, we can see practical examples of its lessons in nature.
Par'o once again refuses, and this time he threatens death (he had Moshe's in mind - G-d "took it" in a different way) if he sees Moshe again. He thus inadvertently prophesies his own demise.
G-d next tells Moshe of the final plague, which will cause Par'o to hasten to expel the People of Israel from Egypt.
G-d instructs Moshe to tell the People to borrow gold and silver from their Egyptian neighbors.
G-d "reminds" Moshe that there is one more plague (the "real" one; the one that was presented up front, the one mentioned before all of the others) and then Par'o will send the people on their way.
G-d tells Moshe to tell the people to "borrow" things from their neighbors. He says that the people will miraculously feel kindly towards the Jews (even though the Jews are responsible, in the eyes of the Egyptians, for the hard times they have been suffering). G-d implanted in the eyes of the Egyptians an admiration and respect for Moshe.
[SDT] Par'o usually called for Moshe AND Aharon when he wanted to have a plague ended. With Darkness, he calls just Moshe. The KLI YAKAR explains that Par'o was aware of the story from Moshe's infancy that after being hidden for three month, his parents were not able to continue hiding him. This, explains the Midrash, was due to a light that appeared when Moshe was born. Par'o felt that the person who could dispel the darkness would be Moshe alone.
Moshe says, in G-d's name, that He (G-d) will kill ALL Egyptian firstborns, that the screaming from the killings will be unprecedented, and that in total contrast, utter tranquility will reign in the Jewish area. G-d says that Par'o will once again refuse even this threat, so that the full course of wonders and miracles will benefit the People of Israel.
[SDT] One commentator says that Moshe was distraught by the extent to which Par'o went in his refusal to let the People go. Such dedication to wickedness in the face of such devastating punishment was truly disheartening to Moshe. How can the power of evil be so strong? How can someone fight against it and hope to win? G-d's answer was that it was He Who hardened and strengthened Par'o's heart. Left on his own, Par'o would have given in long before. Theoretically, G-d could do this to punish us, but in this case it was for our benefit.
The S'fat Emet marvels at the fact that only G-d would give the power to a wicked person to oppose Him. Why would G-d give Par'o the ability to defy Him? In order to bring about the marvels and wonders of the Exodus, so that the People of Israel shall know beyond doubt that G-d has taken them out of Egypt.
MAKAT B'CHOROT hit from the firstborn of Par'o to that of the servants. Why should the plain members of society suffer for the sins of the rulers? Because they too helped with the enslavement and oppression and rejoiced in it. Thus the commentaries say of Egypt more than 3300 years ago. We saw the same behavior only 55years ago with the fine German citizens who want us to believe it was just the Nazis who were responsible for the Holocaust.
[SDT] The Torah describes the tranquility of the Jewish area with the statement "a dog didn't even bark". Dogs usually sense death and instinctively react. To highlight the contrast between the Egyptians and the Israelites, the dogs were miraculously silent. In "tribute" to the dogs for their role in bringing greater honor and appreciation to G-d on the night of the Exodus, the Torah rewards them by telling us (elsewhere) to throw our "treif" meat to the dogs. (This applies only when a forbidden food is NOT also forbidden to derive other benefit therefrom.) Thus we have an unusual lesson in HAKARAT HATOV, acknowledging the good that another does for you.
[SDT] "No dog wagged its tongue" - The Chidushei HaRim sees this as a reference to the terrible sin of Lashon HaRa, gossip and slander. It can be said that Lashon HaRa caused us to be enslaved in Egypt. The Torah tells us that Yosef brought evil reports about his brothers to their father Yaakov. Their hatred for him resulted in his descent to Egypt and subsequently brought everyone else down there. Secondly, it was the Lashon HaRa of Datan and Aviram who informed on Moshe to Par'o, that he (Moshe) had killed an Egyptian, that put Moshe's life in grave danger. Redemption could not (would not) occur unless we had "straightened out our act". The Midrash tells us that the Jews in Egypt managed to keep the secret of the reason for our "borrowing" Egyptian vessels from our neighbors, for twelve months! A people who can manage not to divulge this information for a whole year has succeeded in purging itself of the temptations of R'chilut & Lashon HaRa, and merits redemption.
G-d commands the setting up of the Jewish calendar . (Lots on this mitzva all the time in TT)
He then commands the taking of a lamb or goat for each household (approx.). The animal was to be taken on the 10th of Nissan (this rule was for "Pesach Mitzrayim" only and not for future Pesachs; therefore it is not counted among the mitzvot of the Torah) and held for the 14th of the month, when it was to be slaughtered in the afternoon . Its blood was to be smeared on the doorposts and lintel (only that first Pesach). The sacrifice is to be eaten on the night of the 15th of Nissan , having been roasted, with matza and maror (this being part of the mitzva "for the generations", but not counted separately among Taryag); that is, neither cooked nor partially done , but roasted whole. No part was to be left over until morning ; any leftovers were to be burned. It was to be eaten with "belt tied", in haste, ready to leave (details for Egyptian Pesach only).
It is a bit confusing to distinguish between the details of the mitzva of Korban Pesach for all generations and those elements of the story of the Exodus which were meant only for that first Pesach. In fact, it is not just confusing; it is impossible to completely differentiate between the two categories of details... WITHOUT the Oral Law. The Talmud informs us as to what constitutes the mitzva of Korban Pesach. The Written Word is incomplete. Our Torah consists of two inseparable parts - the Written Word and the Oral Law (embodied in the Talmud and other sources). This is a fact that is reinforced over and over again throughout the Torah. If one attempts to understand the Written Word without the Oral Law and Tradition, there will be confusion at best and distortion and perversion of G-d's Word, at worst.
Then G-d will "pass through" Egypt on that night, kill the firstborns, and "pass-over" the Jewish home with the blood-marks. This shall become a holiday for all generations. Matzot are to be eaten for seven days and on the previous day (Erev Pesach) Chametz is to be eliminated from our homes . (Eating of Chametz on Pesach is a rejection of membership in Klal Yisrael, hence the punishment of "excision".)
The basis of Yom Tov is set down in 12:16 - specifically that Melacha is prohibited, as it is on Shabbat, with the exception of "that which is needed for food".
The Oral Law and Rabbinic legislation combine to define that which may be done on Yom Tov. It is far more complicated than the pasuk seems to indicate. Logic cannot always explain the way things work out.
The source of "sh'mura" matza is in 12:17. The mitzva of eating matza on seder night  is followed by the prohibition of possession of chametz during all of Pesach . Foods containing chametz are also forbidden .
Because the prohibition of chametz and the mitzva of matza are linked to each other in the same pasuk, we do not view Matza as a purely positive time-related mitzva. We might have thought that women would be exempt from the mitzva of matza; they are not exempt. In fact, women are obligated to perform other Seder night mitzvot as a package deal with matza. Specifically, women are obligated to fulfill the mitzva of Hagada - they should not be silent observers at the Seder table, but should participate in transmission of the story and details to their children and guests. Women are also obligated to drink four cups of wine. Our Sages give an official reason for this requirement (and that of Megilat Esther and Chanuka candles, as well) - "For they too were involved in the same miracles. " There are technical differences between the "official" reason for a woman's obligation of a time-related Torah law and a Rabbinic Mitzva.
Moshe gathers the elders of the People and relays G-d's instructions. He also tells them that when the People get to Eretz Yisrael, they will continue to commemorate the events of the Exodus, with questions and answers between the generations. The People do as commanded. Note the familiarity of the text (think Hagada) but also note the different combinations of questions and answers between the Torah and the Hagada.
Notice something. Not only is going into Eretz Yisrael part of the Promises of Redemption, but in the statement of the laws of Korban Pesach there is reference to "when you will come to the Land..." To the tachlis aspects that they had to attend to, is added the Package Deal aspect.
It comes to pass, that the Egyptian firstborns are smitten, that the Egyptians shower the People of Israel with gifts, and hurry them on their way. The People leave in such haste that they take quick-baked breads with them without taking the time to let the dough rise. Approx. 600,000 men plus women and children leave Egypt, together with many Egyptians who are smart enough to flee with them. Thus ends a 430 year period of exile (according to some reckonings, this is the length of time from the prophecy to Avraham at the Covenant between the Parts and the Exodus). That night shall be a special night for all of Israel throughout the generations.
[SDT] The period of Egyptian "Slavery" is given as 400 years and as 430 years. An interesting Drash on the extra 30 years is that it corresponds to 210 yrs. of Shabbatot. A reasonable master would allow his slaves one day a week off. Par'o was excessively oppressive, not allowing the Jews to rest even one day. These extra30 years of Shabbatot are acknowledged by G-d, so to speak, by being added to the total.
The Torah now shifts from relating the story of the Exodus back to the rules for the Korban Pesach. Jews who have "left Judaism" and embraced another religion , non-Jews, even those who are committed to the Seven Noahide Laws  may not eat Korban Pesach. The Korban must be eaten in one place; removing it from its place is forbidden , as is breaking a bone in it . Only Jews participate. An uncircumcised Jew may not eat of the K.P.  A true convert to Judaism is equal to a born-Jew. The People did as commanded and on the day in question the multitude left Egypt.
Observation: There are some parts of the Torah that are completely story-telling. The Book of B'reishit is a good example. (This is not to say that we don't learn things from the stories in the Torah.) Some parts are solid Mitzva. Parts of Vayikra and D'varim fit that description well. And other parts of the Torah are an interesting blend of story and mitzvot. Parshat Bo is an excellent example of the blend-type sedra.
As a commemoration of the Exodus (specifically plague #10), we are commanded to sanctify firstborns (human, kosher farm animals and donkey. Each of these categories of "b'chor" is treated differently) . The Torah sets down the continuous observance of Pesach, even after entry into Israel.
The sedras of Shmot, Va'eira, Bo, B'shalach give us a good way to start gearing ourselves towards Pesach before the panic sets in.
Here in Parshat BO, we have the general command concerning the sanctity of the firstborns and the specifics about one type - the firstborn donkey. Elsewhere in the Torah are the details about firstborn humans and those of the 3 types of domesticated animals - cow, goat, sheep. A human firstborn MUST be redeemed. A kosher animal eligible for the MIZBEI'ACH as a sacrifice MAY NOT be redeemed. A firstborn donkey SHOULD be redeemed.
Specifically, the firstborn (if it is male) offspring of a donkey may not be used by its owner until it is officially exchanged (redeemed) for a sheep or the monetary equivalent of a sheep. The sheep (or money) is given to a Kohen as one of his 24 gifts of the Kehuna. The baby donkey then becomes the full possession of its owner.
According to the Torah, if the donkey owner refuses to redeem it, he must destroy it. Although this too is counted among the 613 mitzvot of the Torah, it is clear that the Torah "wants" the owner to redeem it and not resort to the terribly wasteful alternative.
Although one can get out of this mitzva by selling a part interest in the mother donkey to a non-Jew before the firstborn is delivered, the Shulchan Aruch forbids doing so, since the opportunity to do a mitzva would be lost. The reason the Shulchan Aruch had to warn us NOT to get out of this mitzva is that in the previous section it taught exactly that method of getting out of the mitzva of the firstborn of a kosher animal and required us, by Rabbinic law, not to allow ourselves to have that mitzva of B'chor. In other words, the same "legal technicality" (partnership with a non-Jew in the expectant mother) will succeed in our not having a mitzva to perform. In one case, kosher animal, it is too problematic without a Beit HaMikdash to allow the mitzva to exist (so to speak). In the other, donkey, the mitzva can be performed with no problems, and so it should be performed.
Chametz may not be eaten  or even owned  on Pesach. It is a mitzva to relate the story of what happened  at the Seder. T'filin also serve as a reminder of the Exodus.
Pesach must be in the spring, the time of renewal of nature. (This requires Sanhedrin to periodically add an extra month to postpone Pesach, so that it will always be in the spring. When there is no Sanhedrin, we have a fixed pattern for 13-month years; when there is a Sanhedrin, it has discretionary leeway within specific guidelines.)
Rambam states clearly that the two components of the Jewish calendar - Kiddush HaChodesh, the sanctification of the Month and Ibur HaShana, the intercalation of the Year, shall be counted as a single mitzva (numbered as  above). He notes that there are two separate p'sukim that command these two different procedures; he nonetheless insists that they are part of a single mitzva to make the Calendar. Ramban disagrees and counts each as its own mitzva. This is one of many points of disagreement between the Rambam and Ramban on the counting of mitzvot.
A first-born-male donkey must be redeemed  or destroyed  (a less desirable alternative).
The Torah reiterates the significance of the younger generation asking and receiving answers and explanations about the origin of the Nation.
The T'filin connection is also repeated. The two final portions of BO join the two first portions of the Shma as the four passages of the Torah contained in each of the two T'filin (written together on a single strip of parchment in the "shel yad" and on four separate parchments inserted into four distinct chambers in the "shel rosh"). The last 3 p'sukim are repeated for the Maftir.
Parallel to the sedra, Egypt's downfall (at the hands of Bavel) is prophesied. (It is quite rare that a prophecy to another nation is used as a Haftara.) Israel, however, shall not fear; G-d is with us! The pasuk that assures us about the Ultimate Redemption mentions that it might happen in the distant future. Nonetheless, we shall not despair. This can be seen in context of the well-known notion that the Mashiach will either come "in his appointed time", or sooner. It depends upon us.
Rabbi Dr. Julian G. Jacobs in A Haftara Companion points out additional connections between sedra and Haftara. Locust are mentioned in both the sedra and Haftara. In the sedra, of course, locust is the 8th plague, the first of three mentioned in BO. In the Haftara, the Babylonian army is compared with the countless nature of swarms of locust. Aside from Egypt facing defeat in both sedra and Haftara, Egypt's deities are singled our for Divine destruction. In both sedra and Haftara we find that the underlings of the leaders of Egypt are much more in grasp of the reality of the situation they face than their leaders are.