When will my interview be scheduled, I became documentarily qualified on 20th Dec 2019?

With all the US Consulates and Embassies being closed ... I predict not before September 2020.

Is H1B petition possible while on furlough?

It is not necessary to repeat your question. Please see my more detailed response.

How how would I be able to get my mother-in-law over here from Mexico on a temporary visa to visit grandkids?

Talk to an attorney in private. To be honest, unless she has more than property in Mexico, it is nearly impossible to bring a grandmother into the...

I am a lawful permanent resident and can I apply for unemployment benefits?

If you use the phrase Unemployment INSURANCE ... it will help you to understand that it is not a public 'benefit. Yes, this will be OK.

Under the current circumstances, can an F2 status holder receive work authorization due to hardship? Spouse of the F2 is on opt.

I agree with my colleague ... COVID-19 isn't an extreme enough situation ... yet.

If I use an AOS EAD will my F1 status be automatically invalidated?

Automatically invalidated? No But at the AOS interview, it can be an issue ... unless your AOS is based on marriage to a US citizen. PS ......

Switching to EAD and back from H1B status?

This looks like a repeat question ... talk to the lawyer that did the I-140/I-485 & H extension ... this is too complex for a general information...

You need to pay a lawyer ... one that said he/she will help you fight ... don't just make phone calls to different lawyers.

I already applied for I-751 waiver Can I get married with someone who's is out of country?

This is a very BAD IDEA ... it implies that your first marriage was primarily to 'gain' a greencard. Be patient.

Switching to EAD and then back to H1B?

Your situation appears quite complicated ... you need to talk to the lawyer that did the I-140/I-485 & H papers.