Exchange to Urumqi, Xinjiang, China?

Hello,

Later this year in September I'm going to be going on an exchange to Urumqi.

I know that the ethnic minority there are Uighur people and I don't want to be disrespectful towards them and was wondering what the best things would be to wear. I have already bought some long sleeved light tunics, but I don't want to buy a 14 day long supply of tunics as I'd be broke if I did that.

What sort of trousers (length?) are acceptable?

What is something which I could wear there, which I may already have? (I'm fifteen and it's a school exchange, I'll be staying with a Chinese family)

Thanks allot already