questions (spoilers)

I understand that Devon was supposed to be the girl in Exeter when it closed (although she would have to be in her 50s since it closed in the 70s). Was she bringing back the spirits and who/what was in Rory and Amber?

I thought they said something about the box being spelled, so why did the priest put Rory in there? How would that protect him, especially if he was trying to put Devon in there?

I thought they also said that the reason why Rory was possessed was because they were performing a ritual, but they were not doing it correctly. Was that the case?

Why did the fat guy get possessed when Amber was still possessed? I thought it couldn't only jump into 1 person at a time (Rory then into Amber when they did ouija).

Did the priest come back to life or was he dead? Was he really trying to save everyone? Did he know which kid was his?