While I can't speak to a layoff experience, I have gone back to work for a place from where used to work then resigned.
I recommend that you:
1. Bargain hard. Stress the company-specific experience you have since knowing the relationships, culture, and procedures is a big leg-up on the competition.
2. See if you can re-establish pension vesting where you left off. Same for a 401k. If you can resume contributions immediately, that's a big plus.
3. Stall as much as you can (without making it obvious) to see what happens with the other jobs.
4. (maybe) if they offer you a job (and you accept) and later one of the other positions comes through, you can always...well...quit the current place and go work for the other place. Just make sure if doesn't matter if you burn bridges or that the respective bosses aren't golfin' buddies. It's a SMALL world. But this sort of thing happens all the time.
But by all means, look out for no. one.