@8: As a guy who likes to wear girly clothes, what I can tell you is that a lot of crossdressers are turned on by gender play in general. Beyond just the clothing, a lot of us tend to find the mental image of ourselves as females very sexy. You'll want to talk to him about this, of course, but he'd probably be interested in things like pegging and other role-reversal type play.
You could also ask questions over at http://www.reddit.com/r/crossdressing
(I actually posted a link to this page there, earlier.)
Good luck, you sound awesome, and he's very lucky to have you!