a) is definitely a foul for illegal formation, ineligible downfield, and illegal touching. The formations are legitimate SKFs, and with numbering exceptions. However, since A46 was an interior lineman when the SKF was first established, he is then ineligible for the entire down, even when "uncovered" after the shift. Also, since he was an exception to mandatory numbering when the SKF was established, he must be between the ends when the ball is snapped. So, at the snap, A46 is in an illegal position, thus, this is an illegal formation foul. When A46 goes downfield more than 3 yards and a legal forward pass crosses the NZ, he has committed a foul for ineligible downfield. When A46 touches the legal forward pass before it is touched by a player of team B, he has committed an illegal touching foul.
b) is uncertain, because the rules are ambiguous, and there is not an AR similar to this play. The crux of the issue is whether or not the fact that there are NOT numbering exceptions makes any difference. 7-1-4-a-5 says that Team A may have FEWER than 5 linemen numbered 50-79, under the conditions that follow. That implies that this rule only applies if Team A has fewer than 5 linemen numbered 50-79. So, if they have no 'exceptions,' then shifts that uncover players numbered other than 50-79 would be legal.
However, my experience with this rule tells me otherwise. Had a similar play occur back in 2012, and we ruled "legal" formation. However, the play was shown to Redding, and he ruled "illegal." They just simply don't want Team A doing anything that uses the SKF formation to confuse opponents.
c) is clearly legal, since they meet the numbering requirements, and they are not in a SKF.
Robert