1. You need to do the exam before you submit things. The cost varies depending on your DMP; Mine was $400 but I've seen people here saying theirs was as low as $100. When I called to schedule an appointment, the office manager told me exactly what it would cost and what I needed to bring over the phone. From my understanding you can use any DMP you want, just keep in mind that if any followup work is required you'll need to get it done at the same one.
2. The FBI check has to be from the FBI. They take a while to get it done, but that form's not a big deal, so he should submit it now-ish.
http://www.fbi.gov/about-us/cjis/background-checksIt's my understanding that you should use the FBI directly, not a channeler, because a channeler can't authenticate the results.
3. My experience has been that being honest/straightforward is best. He shouldn't volunteer information, but just honestly answer whatever they ask. Since he'll be going back home to VT after a few days, he can bring things that show ties there, such as a copy of his lease. They probably won't ask for anything like that but it's always best to be prepared.
4. I also met my husband on WoW and had a couple of my guildies write letters for us. Apparently meeting in a video game isn't too uncommon, check out this post:
http://www.canadavisa.com/canada-immigration-discussion-board/how-did-you-meet-t67051.0.htmlI did not include WoW screenshots, though I was tempted. I couldn't think of a good way to write captions...
"He's the blue goat chick with pigtails and a big axe. I'm the blue goat chick with the green lasers coming out of my hands. Ignore the other two dozen people, they're just helping us kill that giant spider."