1) Since the helmet was lost prior to the immediate acton of making the catch; although for the life of me I'm not sure how a helmet magically comes off unless it was not properly buckled, therefore creating another foul of Failing to Properly Wear Required Equipment During the Down, my guess- Illegal Participation by B88, ball would be dead as soon as he possessed it at the B20 yl.
2) Personal foul on A22, USC doesn't involve contact. In this instance it would be DBPF since the ball should have been dead at the B20 when B88 possessed the ball without his helmet. Fouls would not offset as we have live ball and dead ball fouls.
9-6-4g is a basic spot foul, foul by R beyond the basic spot. Loose ball play, previous spot enforcement. 15 yard penalty on B advances A beyond the line to gain, 1st down to A, then back them up 15 for the DBPF on A22 so A is back 1st and 10 from the 50.
3) No, previous spot enforcement for B88's illegal participation gives the ball back to A.
My head hurts and I've no idea how right or wrong I am.