if you don't have a Carry Permit you can go to the nearest State Police Building and request a multiple handgun purchase form. i have no idea what it's called or if it has a # but i know it exists. i had several guys run down the street and get them then buy two pistols at the same time. my boss at the time (gun shop owner) didn't have his permit and did this more than once.
as for the multiple hand gun purchase, if you buy more than 1 handgun from the SAME dealer in any 5 day period the dealer has to turn a multiple handgun report (forgot the number of that form too). there is no "extra" form if you buy the pistols from different places.
when it comes to rifles and shotguns, buy as many as your little heart desires. (if you buy 20 AK's and get a visit from a guy in a suit, that's on you)