HOAH replied to my questions and I have confirmation on a few things, but nothing is still concrete unless otherwise stated since he may still change his mind, but so far here is what I know 

1. Classes are open to anyone as long as they pass the requirements for that class so everyone can be with anyone in a class regardless of year and house. 
2. Everyone has access to their own private dorm room, but there's still sharing involved with other students. 
3. There will be Ghosts.