Not likely. Usually it is just the opposite orthodontics make the teeth sore and people tend not to grind, but i suppose anything is possible.
Possibly. If you are in the middle of ortho treatment your teeth are being moved. They are not were they started out, and not yet were they will eventually end up. This can cause some people to grind during treatment. If you recently completed braces and are grinding then see your orthodontist. Your bite may still need adjusting. If your finished braces a while ago ; just started grinding then not related.
Vague questions. The best answer to your question is to see your dentist, preferably a tmj/tmd specialist. A thorough history, x-rays, and a examination are imperative to helping you learn more about tmd and point you in the right direction for treatment.