A taking a cheapshot at B will never be USC, it is always a personal foul.
You have multiple live ball fouls by one team during the play and only one can be enforced.
B has the option of taking the illegal formation penalty from the previous spot or taking the PF enforced under all but one.
I'd post rule references but I'm posting this from my Blackberry waiting for the 4th of July parade to start.
Happy 4th everyone!