My B1 visa expired on May 1 due to airport closures.

I agree. Apply for extension of status with a credible explanation why could do so before, on a timely basis. You will need to submit credible...

Which form to file to change my status from L1 to B2? After my change of status to B2, how long can I stay in USA?

The form itself is I-539 and all your questions are best posed during a confidential consultation with a lawyer.

Is it legal for a green card holder parent to receive the simulate check ?

No, it is not illegal to apply, but remains to be seen whether IRS will deem she qualifies.

I-944 questions?

No is the correct answer, as UI is not any type of welfare at US taxpayers' expense.

Can always update the forms with the added name now and also request same during upcoming visa interview.

Yes, daughter needs her own I-751 and filing fee. Biographics is determined by her age.

3 years is the maximum that an employer can request on any H-1B petition

Can I travel to Miami from newyork with ead card ?

The TSA will accept your EAD as valid ID for travel purposes.

Does immigration hold of 60 days impact my wait time for work permit?

The presidential EO has no effect on those seeking to adjust status in the USA.

I-94 extension in respect to EAD validation

Yes, your EAD will only be valid up to the date of your L-2 validity.