Oh, yes. The taxonomy is gigantic, and fascinating (at least to me). (Speaking of, I wonder what linguistic studies have been done on such topics? Hmm, that'd be worth a Google.)

I think labels can be--useful? Sometimes? At least, I'm a big fan of allowing people to label themselves, in a sense. Self-identifying yourself is key, and words are a way to explain/describe your identity to the world. Using "gay" for everything certainly sounds simpler, though, and you have a good point about exclusivity.

"Cisgendered"... I feel like I've been hearing it for a year or so? It's one of those things that's definitely been spreading, though.