Pjiang and others, please help with my EAD and H1

Sorry for bothering your guys again, but I do need your help with my H1B and EAD situation. I am using EAD now and my I-140 has been pending since Oct. 2006.Yesterday, I found out that my i-140 need more evidence. I do not know what kind of evidence they need yet, but for safe side, I want to apply H1-B visa through the company.
My question is if I apply for and use H1-B, does it mean that my 485 application will be cancelled automatically? since my status is changing from AOS to H1-B, is it very difficult to get H1-B approved?

Thank you so much and I really appreciate your help.
Sincerely