Sorry to hear this, Yardpro is right though. Parents try to use their kids against one another in a power game and its sad. The kids have to try not to pick sides. Live life with a smile. If you and your dad get pulled over again, be nice, tell the police after thier questions are done, to have a nice day. Your cooperation and politeness will likely end the harrassment.
As for the troubles between your folks, do your best to remain neutral and don't loose touch with your brother. Give him some support, sounds like he needs a friend. Good luck, hang in there.:(