Ready for play vs. snapper touching the ball (NF please)

[BktBallRef]

I'm involved in a discussion on another board with the following scenarios.

Team A advances the ball and gains a 1st down. There's only 1 second remaining and Team A has no timeouts remaining.

Scenario #1 - The umpire should remain over the ball until the ready for play whistle is blown. The snapper cannot place his hands on the ball until the ready is blown. The offense must then set for 1 second before the ball is snapped. Before the ball can be snapped, time will expire.

Scenario #2 - The umpire should not remain over the ball until the ready for play whistle is blown. The snapper can place his hands on the ball prior to the ready whistle. The offense meets the one second requirement by being set prior to the ready. The snapper snaps the ball as soon as the ready whistle is blown.

Which scenario is the correct way to handle the play, 1, 2, or both?

Can a team actually get a play off under these conditions? Is the snapper allowed to touch the ball, prior to the ready whistle? In your area, does the U stand over the ball until the ready is blown?