[jdw3018]

If the foul is prior to the try being released, the ball is dead immediately and a successful try is cancelled.

2 - while/before: either way, blow the play dead, team control foul, B's ball at spot nearest the foul.

after try is released: common foul by A1. try counts if successful. B shoots FTs if in bonus. B's ball for throw-in if not in bonus.

Edit: Sorry, missed the part where you asked about a foul on A1 after the foul by A2. Read Juggling's response below.