Suggestions pls!!NSC NIW I-140approved, I-485 pending,

Working in university, but boss ran out of funding, give a 1 month notice of looking for new positions. But the openings in my area is not too many, it probably will take me several months before landing a job in similar area. Help, guys, in my situiation,
how long can I stay unemployed?
Can I register into a graduate program in the same field but no RA or fellowship but pay tuition by myself to maitain my status?
If I get a job in some other places, will my cases move from NSC to other center? Which one is the worst place now?


Thanks a lot!!