Our lawyer asked us to take AP (all 3 papers), EAD card, I-485 receipt copy, last pay-stub, company's proof letter saying you are working here (if you want).
Since my H1b will expire soon (in 2 months), certainly I used AP. It's very easy. The officer only asked for AP and passport, he didn't see my other documents. (our lawyer said if they ask the status of your I-485 application, just say it's still pending).
After you come back, I think u can only work with EAD.