2) Great!
3) What happens if there are no matches? I would expect an email anyway to let me know it's still working on finding matches.
4) Okay great. Maybe it's just based on personal experience but I'd like you to flesh that out more. My wife and I throw dinner parties for our friends all the time but they are always "guests" and not "hosts" so the lack of reciprocation can be tiresome. Depending on how you figure out the secret sauce, I think people like us would be some of the early adopters/evangelists.
Have you guys thought about "ratings"? I guess you wouldn't want to introduce the idea of negatively rating someone but I think there's something to be learned from Facebook (gasp). After an event, can I like some of the other participants or something similar (+1 good dinner convo dude, etc) to rise those people to the top of the next matches and to start cultivating a community of leaders, etc.