H1b - Laid off - 60 Day grace period

[kunde052]

Hello...I recently got laid off Dec 1st is my last date of employment.

1. When does the 60 day start and end…meaning if Dec 1^st is my last day, when should I leave the US by? Is Dec 2nd considered as my Day 1?
2. In a hypothetical case, if am terminated today and the date on I-94 (I-797) is in October 2023, but the data on the visa stamp is Jan 2023. How is my 60 day grace period counted?
3. My previous company gave me a letter, asking to provide my itinerary back, so they can reimburse to a certain amount to my travel back to my home country. Should I take this amount, even though I do not know if I am going to stay in the US or leave the US? Because they gave me a deadline (30 days) and I have to give them an answer by end of this year. But my H1b grace period is 60 days.
4. When does my clock on 60 day grace period stop…especially when someone started my H1b transfer application? Is it after filing LCA? or after sending the H1b packet? or After receiving the receipt notice?
5. How long does a VISA filing process (just filing, not processing time) take to do H1b transfer usually and how much does it cost usually as well?
6. If I have multiple H1b transfers processed at the same time? When should I tell one of the employers a No or Yes? Assuming I have not started working at either place.
7. In a hypothetical case, I get offers from two companies (A & B). Offer from company A was two weeks before Company B. Because I am in need of making sure my immigration status, I accepted Company A's offer in desperation, and now I got a better offer from Company B, where my career goals align. What happens if my H1b application is in process with Company A and I finish my 60 day grace period….Can the Company B still be able to file a H1b ? Or do they need the H1b approval notice from Company A?