H4 travel and change of status to H1b after landing

[gurunath.sb]

Current Scenario: My spouse is in the USA on an H1b Visa and I am in India with  H4 Visa stamped till Sept 15 2020. Also My spouse has changed Job, so H1b transfer & extension is in progress.

Questions:

1. With current restrictions can I travel to the USA anytime within Sept 15 as I heard a minimum one month ahead stamping is required at the port of entry?

2. If my spouse h1b transfer and extension is approved before Sept 15 -  Can i travel to the USA on Sept 14th as H4 will also be automatically extended & h4 is already stamped with old employer &  valid till Sept 15th?

3. My current employer is filing a change of status i.e from H4 to H1 out of cap while i am in India, will it affect my travel and change of status to H1b? As  Regular processing of H4 to H1b change of status will anyway take up to 6 months.

4.If answer to above question no. 3 is NO, Can i upgrade 
the change of status filing to premium processing after landing in the USA  and will it affect/reduce the probability of approval to H1b? as i will be having a new I94.

5.  Can I start working on H1b once it's approved without stamping on it and also change an employer if H1b is not approved with my current employer?