On the subject of Vulcan trans characters, I just wanted to add that there is definitely gender differences between male and female Vulcans, at least in some ways. They at least sometimes dress differently.
Federation planets are supposed to be free of bigotry, but I couldn't help but think of the really interesting development the Andorians have gotten in the novels. I'd think that an Andorian whose sexual orientation didn't embrace the four gender marriage would face some social stigma. An Andorian who wanted to be with only one or two partners and/or wasn't attracted to the other three genders wouldn't be able to reproduce if they were true to their orientation.
As for how to handle Wesley having a gay relationship, I'd say the point would be to do it the same way his heterosexual relationships were. Wesley had a few episodes where his love interest was the main story. You give Wesley a boyfriend as the main story of the episode, but the point of the story isn't about gender or orientation, any more than it was when he had girlfriends on the show. A story featuring gay characters doesn't have to be about homosexuality any more than a story featuring straight characters has to be about heterosexuality.