1. If go back China and come back with AP, will I lose my H4 status and only have I485 pending status?
YES.
2. If go back China and apply H4, but not approved, is it ok to use AP to come back?
SURE.
3. How to apply H4 visa in Chengdu, still can contact 中信實業銀行,預約嗎?if so, no interview is needed, right? where can I get the contact info. of 中信實業銀行?
GOOGLE.
4. What documents do I need to apply H4 visa;
1.Money (how much, in RMB?)--RMB 830
2. Passport--100%
3. ? form for H4 visa application--DS156&157
4. H4 approval I797 (original?)--YES
5. Marriage certificate?--DEFINITELY
6. Spouse's H1B approval I797 (copy?)--ORIGINAL
7. Bank statement?--BEST
8. Spouse's pay stub?--YES
9. Spouse's Employment verification letter?--SURE
10. Photo for both of us?--THE MORE THE BETTER
What else?
--COPY OF PASSPORT (YOURS & YOUR SPOUSE)
--ALL PREVIOUS H-1B OR OTHER DOCUMENTATION
--ALL OTHERS YOU CAN THINK OF
GOOD LUCK!!