What is my grace period date to stay in USA

I am working on H1B which is valid till Jan-23 and I-94 is valid till Jan-23. My I-140 was approved in Sept-2016.

I resigned from my employer H on Nov-19-2021. And got offer from new company M on Dec 04. Company M filed H1B transfer with premium processing on Dec-14.

I do see following options

  1. If my H1B transfer get approved. Then I don’t see any risk.
  2. If my H1B be get denied. How many days I can stay in USA for job search?
  3. My H1B petition is not yet revoked by company H. Can I go back to company H if they ready to rehire me? Do they need to reprocess my H1B?

Thanks,
R

If you are going back to same employer, same position, your H1B is not withdrawn and is still valid, then there will be no need to file a new petition.