Should I apply for stem opt extension before my opt expires or before my cap gap extension expires?

It is not 'you' H-1B application ... it belongs to the company that paid for and filed it. The company, or their lawyer will get the receipt,...

Can my separated spouse steal my part of the Covid-19 Stimulus?

I have heard that there won't be any checks. Rather, there will be a 'credit' applied to each SSN account to apply to future tax returns.

no No NO Don't try to 'bend' the restrictions on your L ... this is a form of forbidden self-employment.

Unemployment is not a 'public benefit' .. it is an insurance program.

Depndents H4 EAD validity in case of H1B transfer?

1. Do not start working with a new company on a receipt ... even though it is technically legal, more-often-than not it causes future...

I AM FILING OUT DS-260, ONE OF CHILD IS 7 YEARS OLD WHO WILL NOT COME WITHIN A FEW YEARS ?

Talk to an attorney. Quite often it is not a good idea to wait 'a few years' for the child to follow-to-join.

No, if you are filing for an adjustment of status AT-LEAST-90-DAYS after having last entered the US ... US CIS will run the police check for you.

There is no actual deadline. The 'key' is to NOT do anything in violation of your F within 90 days of having last entered the US.

I would like to know if I can continue with my adjust of status with a petition of a waiver and finish my case inside US?

I agree with my colleagues, you don't appear eligible to adjust status ... confirm this with an attorney via Skype.

I am F-1 student, doing my Master's and going to apply off-campus work employment due to COVID-19 ?

You need to talk to the most important person in your life .... your DSO.