Both you and your lawyer will receive the interview letter.

You need to bring I94, passport, your employment letter, pay stubs, tax returns and I140 receipt, Labor Certificate approval, H1B approval, AP, EAD and all you could think of, just in case. When you go to interview, you need to swear first.If your lawyer doesn't come with you, you need to sign that you will complete the interview without your lawyer. Your interview is recorded and videotaped. Don't worry.