I would dance with men in a group along with my female friends, but not one to one (so no 'twerking/grinding/slut-dropping' type stuff or close, slow dances) and would be perfectly happy if DH did the same (to be fair, he is the most "enthusiastic" dancer I have ever witnessed, so would likely have a 2 metre wide zone free around him
).
With regards to flirting, I wouldn't sit chatting intently one to one with a guy, but would happily join in chatting with a group of people (mixed male and female) and would possibly be a little flirty - but I would absolutely mention my DH, early in the conversation. I don't drink, so I'm confident I know where to draw the line, but back in my drinking days (and pre-children) I regularly flirted loads with guys on a night out - never danced with them, kissed or did anything else with them, didn't exchange numbers etc. but did let them buy me a drink!
If it were DH talking to women, I expect he'd find nothing wrong with talking one to one with someone, but would be unlikely to flirt - he's generally quite intimidated by women who flirt with him, unless it's me! I think I'd be ok with him flirting a little though, just so long as he had mentioned the fact that he's married (make that happily married!)
Other than a quick peck on the cheek to greet/say goodbye to members of the opposite sex, I think any further intimacy, such as a cuddle (rather than a quick hug) or hand holding, let alone kissing or anything more, would definitely count as cheating in my book.
Bloody hell, it's a minefield isn't it?! No wonder we never go out out anymore!