There is no point in the game, where advancing another event "too far" will prevent you from seeing another event. You should still be able to get the scene with the maid, no matter what else you did.
The event with Brad's friends at Kagabanui isn't done yet. It'll be added later.
No, you can't visit Bellatrix or any other prisoners at the Ironholm Prison.
I still have years of content planned, so you don't need to worry that I'd finish anytime soon. ^^