What's this hole for?

Nope....just drill the one for the stud, and a smaller one for the screw. Be careful when you reach up into the door to start the nut on the stud. You'll be blindly feeling for the right spot, and if that little sliver that always hangs on when you drill a hole in sheet metal is point just right...it will drag a hunk out of your finger! :BangHead:
you've done that too, lol.