I can answer 4.
People get termed left and right. It is insane in the first few months to randomly see people leave. some of the top reasons are underaged drinking, providing alcohol to minors, having over night guests, harboring terminated cast members, having weapons(everything is a weapon...basically) and there are many more.
those are basically the housing ones and i would just advise you to be careful. I am extremely careful about the decisions I make because I cannot afford to be termed.
(please add anything else I missed)
It is very easy to room with someone. There is a form to fill out and when you check in you can just choose to live with each other.
I cant really answer the others but I can refer you to the website and the disney look tab.