You can live and work in India for whomever you want, until the PERM and I-140 are approved, available, and issued to you at the U.S. consular office.

You can request concurrent employment on two H1b's.

The consular officer must recommend the waiver, unless this is for an immigrant visa. If this is for a nonimmigrant visa, you do not file anything.

The main issue is that you are married to an American. It is up to the discretion of the consular officer.

No, but it is usually a good idea so you can extend the H4 status.

It is not clear from your question why you qualify for adjustment of status [form I-485] or advance parole [form I-131].

If you have a green card you can work wherever you want. If not, by working outside of your field you will raise the issue whether you are going...

He can include the tax return and submit documents demonstrating what his income was. Such as W-2, 1099, Schedules.

They can reenter the U.S. up to the date their visas expire.

You cannot be deported if you are in legal status.