Hey there. Thanks everyone for your input. My parents passed the interview yesterday.
The interviews were scheduled at 1:00pm for my mother and 1;30 for my father. But never an interview would start on time, right
We got called at 1:30. I asked if my parents could be interviewed together as they needed me to interpret. They said ok. To much of our surprises, the IO officer was chinese therefore no interpretation was needed. She was pretty nice. She went thru the question list on the I-485 form. And that was about it as far as formal interview went. She also asked questions here and there about my family, when I came here, how I got my green card (thru work in my case) and how often my parents came to visit me. And since she was chinese, apparently she could understand conversations between me and my parents. Now I think about it, it makes great sense to have someone who understands your language to interview you as it is much easier that way to pick up subtle clues.
I didn't bring in the forms. They had everything. The IO didn't ask about the timing of the support document either. She did pointed out the picture on my birth certficate didn't look like me at all. I explained that picture was taken about 20 years ago and my parents never had any other passport pictures of me except that. And I showed her my old passport which had that picture on it.
All in all, it was a good and smooth process. Was in and out in about an hour. I parked my car behind the federal building. If you drive on broad street south bound, take the first left turn after passing the federal building, follow the sign, you'll see the lot right behind the building.
Again thanks everyone. Good luck if you have an upcoming interview.