We had a student last year, who was lovely. She was very quiet to start with but half way through she started to relax, was very obliging and pleasant. She asked if she could use the shower and was in bed before my daughter. She didn't ask to use the computer, although, we did volunteer it a couple of times for emails to friends. She totally fitted in with our lifestyle. She actually came armed with eight books to read, so she had something to do herself.
To be honest I didn't want to be messing around with food too much, so I gave her two options each day, ie salmon or chicken, cheesy pasta or Bolognese. I put veggies in a dish and left her to help herself or not. We asked what filling she wanted in sandwiches and said if she didn't like something to bring it back, so we knew and didn't give it her again. She was actually really easy to feed and would try anything.
The first night we played on the wii as it was something we could easily do without having to worry about the language barrier. During her stay, we did things most evenings, local walk around the park, on the hill, played a game, looked through our photos and books together, had another girl for tea, my daughter and another friend actually chose to take her around the local shops themselves and bought some fish and chips back for her to try as well. She also had studies she had to do in the evening. At the weekends we went to a castle, into our local town and to a countryside village. She was very polite and readily did all these things.
Regarding your home, all you need to have is one that's reasonably clean and tidy. It's only for a few days, not for life. We have a two bed house and both girls were in the same room which the other girl accepted, despite coming from a six bedroomed home herself!!