KEDUSHA
Let's do some fine-tuning of our Kedusha - Daily Shacharit and Mincha as well as Shabbat and Chag, Shacharit, Musaf, and Mincha. Although there are differences among the Kedushas, there are some basic principles that apply to all of them.

The essence of Kedusha are the p'sukim KADOSH, KADOSH, KADOSH..., BARUCH K'VOD HASHEM MIM'KOMO, and YIMLOCH HASHEM... (There are opinions that only the first two of these three p'sukim are the essential Kedusha, but we will consider all three p'sukim of equal status.)

There are opinions (Vilna Ga'on, Aruch HaShulchan, to name two) that the KAHAL (congregation) says only these three p'sukim, all the rest being said only by the SHATZ (Shali'ach Tzibur, Chazan).

It is a widespread practice that the KAHAL also says the other parts of Kedusha, but attention of the TTreader is called to the following comments.

First and foremost, as was already said, the essential Kedusha is the three p'sukim, which do not change from weekday to Shabbat and Chag, nor do they change from Asheknaz to S'fard, to Eidot Mizrach to Yemenite. They are the p'sukim of Kedusha. They are the only parts a person says when he is in a place in the davening that he may not talk but may participate in Kedusha. (As opposed to situations when no participation except silence is permitted - e.g. in the middle of the Amida.)

N'KADEISH, NAKDISHACH, NA'ARITZCHA, KETER & YACHAD are invitations of the SHATZ to the KAHAL to join him in saying Kedusha. Technically, only the SHATZ should be doing the inviting. However, as mentioned earlier, it is common for the KAHAL to say it too. If so, it is preferable to say (or sing) the intro along with the SHATZ (his voice should be heard above that of the KAHAL). When the SHATZ finishes M'CHYEI HAMEITIM, the KAHAL should say AMEN and the SHATZ should preferably begin N'KADEISH (etc.) right away. KAHAL joins him, hums along, or just listens.

Then all (SHATZ and KAHAL) should say KADOSH, KADOSH... together, with the SHATZ loudest.

If that doesn't work well (shul habit-wise), the SHATZ should start KADOSH, KADOSH... at least before the KAHAL finishes saying it. And the SHATZ should definitely say it out loud, and not just continue with AZ B'KOL (for example). If the SHATZ says KADOSH, KADOSH... only after the KAHAL finishes, it is as if he has absented himself from his own call to the congregation to sanctify G-d's name with the reciting of Kedusha together. Which is the main point of Kedusha.
So too for the other p'sukim of Kedusha. SHATZ calls to the KAHAL to say them, they do not begin the p'sukim until he finishes the sentence leading to it, and then he and they should say each pasuk together. Or at least, the SHATZ should begin his aloud recitation of the p'sukim before the KAHAL finishes theirs. Together is preferable, with the SHATZ's voice the loudest.

If you are going to sing along with the SHATZ (e.g. on Shabbat & Chag) when he says the parts between p'sukim (e.g. Mim'kom'cha), then don't say it a first time; just wait for the SHATZ and join him. Remember that technically, these are parts for the SHATZ. But if you are going to join him, which is the common practice, then at least don't say it twice.

The NUSACH of the shul should be used by everyone. If you usually daven Nusach Ashkenaz, for example, and you are davening in a Nusach S'fard minyan, Kedusha follows the KAHAL. <more to come>