-As long as your employer does not report that you are laid off to USCIS, they will never know it and you will be fine.
Do i need to transfer back to F1 so I don't stay out of status?
-Up to you. If you can find a job shortly, you may just stay. If you can not find a job for longer time (for example, > 3 months), you can go back to school again
Is there a time limit?
-You can legally stay for 60 days after your OPT expires.