Is Fee required for Renewing EAD with I-485 Pending

I-485 was filed on March 2008 when my hu*****and was filing for EB1 and my EAD was filed later...EAD will expire in July. I am currently holding H1-B visa, and will go back to China for a visit this weekend. I have these questions:
1. is form I-765 used for renewing EAD?
2. do i need to pay the fee again or not? from the USCIS website, it seemed that i do not need to pay because my I-485 was filed after July 2007.
3. Do I have to use travel document to reenter US or can I try to get the visa in China and enter with the H1-B visa?
4. If I enter with H1-B visa will my I-485 application be void?

Many thanks in advance!