Yes, it is likely that you can apply for him as a derivative of your U visa. He cannot have been the perpetraitor of the crime, and an attorney should assess the case to make sure there are no inadmissibility issues. If there are, he may be able to get a waiver. Best of luck to you.
Perhaps. But, there are many factors to consider. Meet with an attorney, low cost options exist, see below.
Franco Capriotti - Senior Legal Counsel & Former Professor of Immigration Law - Capriotti International Law - firstname.lastname@example.org
Our services are not limited by State, nor International bounderies. Our licenses allow us to represent people worldwide.
Do not rely completely on information you get on any website. It is always wise to consult personally with an immigration attorney before taking action.
Consider contacting one of the attorneys on Avvo, or www.ailalawyer.com - If you are low income go here: www.justice.gov/eoir/probono/states.htm or http://www.immigrationlawhelp.org/
Capriotti International Law
FORMER IMMIGRATION LAW PROFESSOR -- LEGAL DISCLAIMER: This answer is offered for informational purposes only. It does not constitute an attorney-client relationship.