I do buy early access if it looks interesting, but occasionally I wait until the full release before fully playing through them. Though, this varies per game for me.
I almost always try to go for the good ending first, though I don't always use guides for it so I might end up getting a bad one at first anyway, but I don't go for the bad one by default.
The romance part is the one I actually care about, so this isn't something I'd focus on when looking for a new game. Though it's not a horrible idea if it's done well, so I do see why some people would like it.
It varies per game for me. If I believe the experience to be more interesting while played blind, then I'll do that. Otherwise I'll check specific details of guides to get the endings I want the most.
I'm usually not the biggest fan of yandere's. The forceful toxic personalities they have only make me uncomfortable most of the time. Not a fan of so many of them being made.