Jepy

UPDATE:
I just wanted to let you guys how everything went with my Advance Parole. I came back to the U.S. a few days ago. I had to explain what the AP card was to at least 5 airline employees - first in Bulgaria upon check-in - they were very friendly but just haven't seen that card I suppose, so the guy called his supervisor who has heard of it, but not seen it. It really helped that I had that little piece of paper which explains the combo card and which comes in the mail with it when you receive it. He read the explanation and had no problem with checking me in. Then in Switzerland - the first lady at Passport control before boarding the plane to the U.S. was very confused that I don't have a visa or a green card and why I was trying to board with some other card; she also tried to convince me to fill in an ESTA (my country is not in the visa waiver program). She was really nice though and trying to understand what it was that I had. I showed her the explanation letter too, she read it and seemed to be satisfied with it; then she called her supervisor too and she told her it was ok. So they gave me the OK to board the plane and sent me to get a boarding card at the US Airways desk. There, again, a confused employee. Explanation letter, again. Employee understood. I boarded the plane (Yay!!!) All in all, people were nice to me and it didn't take them a long time to resolve the issue, but it did make me a little nervous.
My POE was in Philadelphia. I went through the US citizens/Permanent residents line which was reaaally fast - the officer there was extremely nice and knew exactly what he was doing. He sent me to secondary processing and people there were very fast and professional, too. The whole thing took me around 10 min. It was great!
My advice is - when travelling with the combo card, bring that explanation letter that came in the mail with it. It really helped me. I also had the FAQ about the AP card from the USCIS website printed out just in case.
Good luck!