1. Is the offensive line required to be balanced?
2. When are you considered to be lined up on the line of scrimmage?
3. Three running backs line up (set) behind the quarterback. All at once they move to a trips formation then get set for one second. Illegal motion or legal movement? If this is illegal, how could the running backs move to that formation legally (and try to catch the defense off guard)?

Thanks.

1..NO

2..Defense: Within one (1) yard of his scrimmage line. Offense: Even with waistline of nearest teammate on the line, within one (1) yard of his scrimmage line..

3..False start: (a) A shift or feigned charge that simulates action at the snap. (b) Any act clearly intended to cause B to encroach. It depends on how the backs move when they shift.

Bob

3. Unless the shift simulates action at the snap, it's perfectly legal.

NFHS:

2. Breaks the waistline of the snapper.... not the nearest player.

About #3
 

Unless the backs made a motion that looked like they started the play, the motion is legal as long as they ALL stand still for one second before the snap.

You're kind of at the mercy of the officials on this one though. If they fool one of the officials, that person will be throwing a flag for false start.

The only players required to stay set until the snap are players actually on the line of scrimmage.