You can avoid it and stop it all together, just keep playing it and the option to stop it comes up through a dialogue choice with her. I'm of the same opinion regarding the BBC race stuff and having it being disabled really helps.
Remember that the saves don't naturally jump with the game. You need to open the previews version, save to disk, then open new version and load from disk.
Well, it's kind of hard to include said fetish without a poc… and while the ntr/cuck content could easily work without one, it's much better done than in other games in my opinion. Take the one 'cruising' on long schlongs for instance. That one has me rage quitting over the fact that the MC can't simply dump his stupid ass phone in the ocean every single time.
You know what I do? I like to pretend I'm just some god in the sky causing the MC to go through with being some depraved sissy or whatever. Kinda as if the MC is a sim. There are a ton where you're corrupting others, but very few involve the MC corrupting another male to become a sissy or female. The only ones that I can think of that do that are My Destiny(probably the best one for this), Friends of Mine, and The Company(kinda), there's one or two others I can't think of off the top of my head.
When you are on the route, where you basicly approve that your girlfriend is making out with her prof, than you can also start corrupting Olivia to be into black guys. Thats what the book is for.
If there is no more content for Lexi, you can see it on the second floor of the Cauldron. There will be a grey message, that says you reached the end of the content with her for 0.4.
Yes on them being missable. I sadly haven't had the time to play the latest update yet, but this is the full list of achievements with in-game hints:
