1. No need to do it in china at all. You can and should do the divorce in
the US even you got married in China. If you do it in China, the US probably
would not enforce the terms regarding money issues like child support
payment.
2. You two negotiate together, go check the price for similar house sold in
your community.
3. Go to your local court for sample letter or forms
4. 离婚后男方需要每月支付女方补助吗?多少钱以及多长期限比较合适?
Depending on your state, most likely no need to 支付女方补助 (this is called
alimony ) since you married for less than 10 years and both of you work,
and the income difference is not huge.
Since 小孩归男方抚养, 女方 need to pay child support to 男方. There is
formula to calculate the actual amount in your state. Child support always
goes with the child, no matter which party have it. This is different from
alimony.
5. Generally no.
6. Go ask clerks in your local court for procedures, or search over the
internet.