I would probably go with an email too, tell him I'm sending an email with bullet points I want to cover, and including a few topics we haven't discussed before, or that were sources of conflict in the past. Probably send it 2-3 days beforehand, and say I don't want to discuss it until our meeting, but that I wanted him to have a chance to think about the topics before the meeting.
I'd encourage him to send me a list of bullet points he'd like to discuss if there is anything not on the list that he'd like me to think about ahead of time too.
I'd be clear that we wouldn't discuss anything until the meeting.
Err, and I'd make sure not to drink in those 2-3 days and go to bed early to stay out of impromptu late night talks!
Really this is because I don't like things sprung on me, I like having a bit of time at least to think about things. Adam usually doesn't have anything he wants to talk about unless he's prompted, so I'd also hope the bullet points would stir up if there was anything he wanted to bring up.
I also dont see a problem with a double standard of who stays over. People I don't like wont stay in my house while I'm home. People who negatively affect my life don't stay over in my house while I'm home. Your bf doesn't live that close, and it sucks to be the one doing all the travel. I would have a few options available to suggest to your husband
bf stays over on nights your husband stays elsewhere
bf stays over and you agree to curtail all potential noise making activities past X pm so your husband can relax and not worry every noise he hears is you thumping against a headboard
your husband agrees he stays over on a night he has plans elsewhere, your date ends at X pm and you go sleep with your husband and your bf sleeps alone.
bf spends a night or two over first and sleeps separately but spends a bit more time getting to know your husband (if they both want to or think that would make it easier) before staying over and sleeping with you. I think the offer to all sleep in different rooms is a great one because it shows your concern isn't being able to get busy in a more convenient way.
now that I write all that out, maybe less is more...I tend to have too many options for my dear husband sometimes...
Happiness will never come to those who fail to appreciate what they already have.