I say back out unless the deal is too good to pass up. Seems like too much trouble to me if you could easily find the gun locally for a few bucks more.
I've bought and sold a lot of guns over the internet over the years. I've used paypal, CC, MO, and never had to jump through those hoops. I've never asked for a DL, and never been asked for one. I've never had to send a copy of the CC, front or back. I would be concerned with security issues over that, since he will then have your CC, copy of your sig., the security info from the back of the CC, AND your SS# if it is on your DL like mine.
I don't see why he can charge your CC and make sure it clears before shipping the gun. But I suppose he wants to make sure the CC isn't stolen. Perhaps there are easier ways to check if a CC is legit without getting all of your personal info.
As far as the FFL, I used to have a local dealer who was convinced that he had to receive a gun in the mail from an FFL dealer. I ditched him fast, because it was too much hassle to explain it to the seller every time, and it was too much hassle to try to convince my dealer that he was wrong.
To me, the biggest red flag is that he will not give you his phone number. It's pretty standard to speak with a person by phone before finalizing a big dollar transaction. That's pretty suspicious. Not to mention only 1 feedback on gunbroker??? Hell, for all you know, he found a dealer on EBAY with a high rating, and he has been using the same USERNAME and claiming all the feedback as his own.
Anyway, I wouldn't risk it myself, but it's your money.