1 - I don't reccomend playing music out loud (unless it's super quiet so no one can hear you). This is just my personal opinion but I just think it's a little inconsiderate since some people might have trouble concentrating while studying, sleeping, etc if they hear sounds.

2 - Most people do their makeup/hair in their rooms just because there's a mirror in the room so it's pretty convenient and more privacy. But if you wanted to do it in the washroom instead that's definitely okay. It's pretty rare for anyone to have to wait to take a shower so you don't need to worry about how long you shower.

3 - The reason why the fridge is there is for your personal use! So don't worry about making stuff for other people.