Anyone with a child with this disorder?

My niece who is almost 5 has Asperger's Syndrome. I know a few facts about it but not a lot. When she comes over she plays by herself and doesnt really like to talk to people. But recently the only thing she is talking about is cars and the solar system which I think is pretty weird. Anyway can someone please give me more info on how to interact and handel her. Shes a pretty good and calm kid but she likes to do the same things everyday like everyday she eats by 6 is in bed by 7 and goes to bed at 8. If not she throws a fit and doesnt really like change. Im going to baby sit her for a week because her parents are going out of town and I could really use some advice and info about what I should do and shouldnt do and the best way to handel her if she does throw a fit or wont intract with me. I would like to have a realationship with her.