Let me caveat off the last post as well...

High Schoolers in the US, unless it is a boarding school, don't live on campus. You would need to find a family to sponser you and house you.

Relations between American students and foreign exchange students are almost always very good, as the American students will be very curious about your way of life. You should have no trouble making friends, and they will help you brush up on your conversational English.

If you are coming over to look at schools, I'm wondering how you are going to get out to them. You are probably too young to rent or drive a car, and the public transport system in the USA is not quite near those in France or Norway. You will be more or less restricted to the areas around bigger towns, unless you are going to meet someone over here that is going to take you around.

Good luck, though, and enjoy your visit.