illegal motion??
 

A80 is on the LOS as a wide receiver and end man on the LOS. After everyone has been set for 1 second, A80 goes in motion to a position off the LOS about 2 yards and is still in motion when the ball is snapped. Therefore he becomes a back. No problems with having enough players on the LOS. I found rule 7-2-7 that says this is an illegal motion penalty at the snap, but am looking for confirmation that this is indeed correct.
Secondly for A80 to prevent a penalty after his motion, he would have had to either reset for 1 second or been 5 yards behind the LOS at the snap. Is this correct?

It is IM at the snap in the play you described. In your "secondly" question, not only does he have to reset for one second, but he has to do so while no part of his body breaking the vertical plane through the waistline of his nearest teammate who is on the LOS, thus establishing himself as a back.