Question: The photo that Sy got off the market stall, (the old photo of a women) he said to Nina that, that was his mother, was it his mother, or did he just say that to make himself feel better, and if so, why would he lie about that?
Answer: It wasn't his mother. He was just trying to fit in and make himself feel better. There is a scene earlier of Sy buying the photo at some type of vendor. Maybe a swap meet.
Question: At the very end of the movie, when Sy's camera ends up having only photos of "the little things" as opposed to the pictures of the other characters pretending to have sex, I interpreted it as Sy not having actually TAKEN pictures of the couple, but really taking pictures of the room itself, on purpose - so that the pictures wouldn't get out, but instead he would just be giving them what he feels they deserved. However, on a couple other websites I have found the ending interpreted as Sy having hidden or disposed of the film that he took the lewd photographs with. Are either of these considered to be "correct"?
Answer: There is a line from the cop at the very beginning of the film in the interview room with Cy "We processed the roll of film we found in your bag Mr. Parish, they're not very pretty pictures. Also you left a camera in the hotel, we processed that roll as well. "As he talks about the second roll he indicates the folder containing the photos we see at the end. Therefore we can assume the "not very pretty photos" found on the roll of film in the bag are the lewd ones of the pretend sex acts. Whether he left the other ones behind as a cover or what he intended to do with the lewd ones we can but guess.
Question: How did Sy know that William and Maya had ordered room service in the first place?
Answer: It's an easy assumption to make. And who wouldn't open the door to room service?
Chosen answer: This is mentioned on the DVD commentary - it's deilberately open ended so one can interpret it as either it's Sy imagining what he wants to happen OR it's what really happened.
Neil Jones
As Neil Jones said, the ending is open for interpretation. However, I think there is reason to believe that Sy imagined the photo. It shows him and the family outside of their house, all looking happy together. Would they want to take such a photo with Sy after the incident at the hotel? And before the incident, they were probably not close enough with Sy that he would be in a photo taken at their home. Him and no other guests/visitors.