Properly prepared ... with at-least 5 affidavits and LOTS of joint tax/financial/insurance/rental records .. assuming that the couple is still...

How to get married overseas and bring spouse before I485 is approved during quarantine?

Yes, this can be a problem. Have you investigated proxy marriages? They're not legal in all states, but they are legal in some.

Can I get B1/B2 visa?

You didn't need to re-post the question with a minor change. The key will depend on how many 'ties' you re-established back home.

Can i join a new employer while current employer H1B petition is pending?

I assume you're on OPT. WAIT for A's papers to be approved before going to B ... around late October.

What is the process to upgrade or withdraw I30?

It can not be 'upgraded' ... but, your father can send a letter of withdrawal, along with a copy of the receipt.

Change of payroll to home country due to loss of pay. What’s the impact on I485/EAD

Do you have an advance parole document? If so, this should be OK ... as long as they give you the promised wage when the 485 is approved.

Having H1-B visa plan to work from India two months on US payroll

Why are you re-asking the same question?

Does USCIS accept/receive letters by mail during national COVID-19 emergency?

Yes, they receive mail. What was the purpose of the letter & where did you send it?

Will my B1/B2 get approved ?

You mention the I-130. But, I'm assuming you meant the I-485 AOS application. What was the basis for the AOS? Did immigration eventually...

Immigration?

Tell your brother to go to www.ailalawyer.com and to find a 'real' immigration lawyer in his area. Most of us are more than happy to talk to a...