A. If someone needs a lawyer there is certainly nothing wrong with providing them with valuable information about someone who can help them. You can't just open up a phone book and assume that any lawyer will be able to give you the expertise and the professional relationship and conditions that you need, so a referral can definitely be a win-win.
At the same time, there are two ethical issues that need to be considered here.
The first issue is the fine line between advising and selling. The Torah tells us, "Don't place a stumbling block before the blind". (Leviticus 19:14). In Jewish tradition, this means creating any obstacle to a person’s pursuit of his/her own self-interest. Rashi's commentary explains that "blind" means "someone who is blind to the affair" at hand. He gives the following example: "Don’t advise your friend, ‘Sell your field and buy a donkey’, when your hidden intention is to buy it from him."
The problem is not the conflict of interest per se; a person is allowed to give a recommendation or a testimonial in return for payment and this is a common selling practice. The problem is the hidden conflict; the person is representing himself as an objective advisor when in fact he has a hidden intention to encourage a sale that benefits him.
This issue definitely arises in your case. Even if you don't get a fee from your friend, part of your intention is to give him business, not only to benefit the customer. Since your profession is to deal with the business side of the deal, your referral could be taken as an objective recommendation.
Another problem is intervening in an existing professional-client relationship. While this relationship is not sacred, Jewish law does give significant recognition to such a relationship. The glosses on the Shulchan Arukh tell us that in some communities it was actually forbidden to intrude into an existing professional relationship (1); this extreme code of conduct was not widely adopted, but it is still expected that existing, satisfactory professional relationships should be respected.
Both of these problems can be averted by stating your referral in an accurate way. For example: "I have a friend who is very experienced in these contracts, I would be happy to give you his number". This expression deals with the first problem, because it makes your personal interest in the matter clear -- you have stated that the lawyer is a friend. It deals with the second issue because you are only offering information and not pressuring or urging the client to abandon any existing professional relationship. In this way you can provide valuable information to your customers and help out your lawyer friend without risking misleading or intrusive conduct.
SOURCES: (1) Rema, Shulchan Arukh Choshen Mishpat 156:5.