Immigration question. My M visa expires in Novemebr. Can I change my status from M to a

Yes, you may apply for change of status on Form I-539.

Yes, the "preparer" need to identify herself as such and sign.

I am On H1B working for a employer at a client location. Can my employer state covid as a reason for not paying me ?

Employer is not allowed to do that and has no excuse for not filing an amended petition.

So if get laid off on H1-B? When the grace period begins? Last day of work? or Last day of payCheck?

Last day figure on employer's payroll records.

Depending on how long the principal H-1B has been outside the US at the time, could face a difficult situation at the airport and must have an...

65 year old at edge of retirement , with I140 approved, can stay n USA without work?

Cannot. The whole purpose of an I-140 and I-485 which ensues is your intent to work after approval.

Can non-immigrant(student f1 visa) change name after marriage with US citizen ( but before apply for green card ) in Florida ?

Yes, can go ahead and change name after marriage.

Consult with an attorney confidentially. This is not the proper venue.

H1B Dropbox

Check the drop box requirements at the consulate in question if you haven't already done so.

Whats the process to continue H1B status if USCIS didn't give any decision on our petetion and 240 days time limit is passed?

Yours is not a situation to be dealt with on a general, free blog manned by volunteer lawyers.