SS IS income so you were supposed to file.  No, you won't be eligible.  The longer you wait to file, the more you will have to pay in penalties and interest. 

No your not eligible. It's only for people laid off work or sick with corona virus.

Doubtful. Not final yet anyway.  I probably won't either...no earned income.

There is no payment authorized as yet. Until there is no one knows what the criteria be for who gets it.