I'm not sure if I can help much with day-to-day life as DD is in a state-run boarding school in the US, and they only take students age 13+. It's run on a shoestring so nothing fancy - it looks like a 1970s UK comprehensive school basically.
They have up to 4 per room. They can bunk their beds for more space. They each get a small chest of drawers and wardrobe and desk. They can stick hooks to doors, and they can put up posters etc. They generally organise it so they have one fridge and one printer per room (students bring them). Some bring futons or beanbags.
The bathrooms are pretty poky and nasty but there are enough of them.
The students are divided into 4 wings, 2 for girls and 2 for boys. They have a shared lounge that has a big TV, lots of tables, lots of board games and lots of sofas.
They have a lot of clubs and things to do. They regularly do mall trips, movie trips, ice skating, bowling, skiing. They have residential staff who live on site and who hang out with the students a lot - they'll have them over for tea, or do organised things with them.
They have free sports every evening, so they play basketball, badminton, ultimate frisbee, they can swim, use the gym equipment.
They sometimes do a movie night in the pool. They have loads of social events.
They are allowed to sign out and walk to the nearby shop or pizza place, but they have to go in pairs. They can also go out running or cycling or for a walk, again only in pairs.
They start off with fairly strict rules as to when they are expected to be working on homework, but if they maintain a B grade or above then they are pretty much left to it. They have wifi but it's switched off at 11pm when lights must be switched off.
They come home at least once a month - they're actually transported to various parts of the state by bus. I don't think this is normal for a boarding school...
It has a really really lovely community feel to it. The kids all spend a lot of time together and are very close. It's like a huge family. Some people argue but mostly it's very supportive.
The food is pretty awful especially if you're vegetarian, but there are a fair few options at each meal, and there's always a salad bar and soup station.
They have a nurse, and a counselor comes in regularly. If your child gets sick then they stay in their room and have food brought and are regularly checked, and taken to the doc if needed. If they're likely to be sick for more than a few days you come and get them, and bring them home.
I'm not sure if that's helpful, but I have to say DD really loves it. I like visiting her there but I would find it very claustrophobic to live there.