A visit is the best idea, although the more you know before you get here the better! Finding accomodation is not that easy, especially in popular areas. Good websites are
www.homegate.ch and
www.comparis.ch . At least you can see what is available right now. Another piece of information about ISZL is that they finish for the summer holiday on 22nd June, and I'm guessing the other international schools are similar, so if you want to see the school with kids still there, plan a visit before they finish! Which country are you moving here from?
Good Luck!