H1B employer change while H4 attending consulate for stamp (Dropbox) - H1B Laid off case

[chandus8]

Please bear with me for writing this detailed information because it is a little complicated. Also wanted to provide more details so that it will not be confusing. 

I am a H1B primary holder and trying to change my employer due to laid off from my current company on 03-Jun-2022. Two weeks back (before I knew about my layoff) my family travelled to India for vacation and they have a visa appointment on 23-Jun-2022 opted for drop box option. DS160 contained all my current employees (who laid off me) documents, visa, i797 etc. In fact, we tried travelling last Dec '2021 and collected employment verification letters but we couldn't travel due to Corona. So, I have the same 7 months back employment letter. Collected last 3 pay slips and the latest is 15-May-2022 to 31-May-2022 which I received on Jun 1st. I will be getting 01-June-2022 to 03-Jun-2022 (3 days) but they promised me that they give 15 days pay till 15-Jun-2022. Not sure, it may come as final settlement or as pay stub format. In this regard, I have the following questions.

1. Trying to reschedule H4 (only my family there in India now) consulate appointments to Aug'2022 but not getting (still trying). If Not then should my H4 dependents appear at the consulate as scheduled on 23-Jun-2022 (Drop box)? If so, will the old employment (7 months back) letter matter for the stamping? Will they ask for the Jun1st to Jun15th Pay stub? If that shows as a final settlement then will that impact?

2. Will the H4 appearance to the consulate on Jun'23 will be impact anything to me (H1B holder) in reducing the grace period of US stay? Since it is lay off and I do not have the latest employment letter?

3. Is cancelling the scheduled appointment the best option until I get a new job? Once I transfer my H1B to a new employer (still searching for the new jobs) then file a new DS160 and schedule a new appointment ?
Here I will be losing around Rs. 40,000/- and not sure whether I will get a consulate appointment immediately or not? My kids' schools will start by next Sept. And return tickets are in Aug 2nd week.

4. There is one suggestion that we can file one more DS160 and carry both old and new by rescheduling the existing appointment. Can we do this? Which DS160 will be mapped to the USCIS appointment application? Did anyone go through this?

5. If H4 attends as it is on scheduled appointment on Jun 23rd (drop box) by dropping an old employment letter and the latest pay stubs, and if by god grace approves then is it again required to go for a stamp for the new H1B transfer (after changing the employer)?

6. Employment letter is it mandatory ? Even after providing the latest pay stubs? Did anyone go through this and get success?

7. What would be the max grace period for the H1B to stay in the US without a job (Pay stubs)?

8. If I go back to my old employer (consulting firm) who has not revoked my H1B and I140 (still valid) and after getting the project still required to do the H1B transfer or simply amendment is enough? Just I moved to my laid off company 8 months ago.

Thanks in advance.