As to the second question, I think that's where Coe and/or the other children may come in. Coe made that cryptic statement about how she was never in the living room and educated people could figure it out. His statement suggests that the child was kept in the second bedroom IMO, and if men were in the same room or taking the girl places it was clear what was going on. If Coe told LE that she was being sold, they may not have believed that he was not a John and involved.
Even the 7 year old brother would know if she was in a bedroom with MAM or other men, even if he didn't understand what was happening. I think LE asked Coe not to tell the press about that information until they found the child or the man/men involved, because they didn't want her killed before she was found.
Once they have that information all they need is for MAM or AD to confirm it, or run the forensics once they find the remains.
On another point from other posts: I don't think that MAM deliberately walked in front of the camera at the hotel. I doubt that he even knew it was there. I think that he went there for purposes of abuse by himself or someone else, perhaps because the 911 report was not part of the plan and he never expected a missing persons report to be made. I think he got word at the hotel that the police had been called.
If all he wanted was to create footage of her alive (and I don't really think that would help him much) there are much better places to do it that don't implicate him in abuse as does a hotel room. He could have walked into a large store and had the video plus plenty of witnesses.