Visible crew/equipment: When the priest arrives and when he later walks to the house, lighting screens are reflected on his glasses.
Visible crew/equipment: In the scene where Bill Pullman is in his office room, in the mansion, the 3 ghosts lift him in the air, you can see the wires lifting the chair.
Answer: The Ghostly Trio were, at the time, playfully teasing James, so Fatso wearing something else instead of what Amelia was seen wearing in the photo, was just a way for them to have some fun at James' expense. At the end of the movie however, they did keep their promise and let James have one final chance to speak to his wife.
Why that specific outfit, though?
Again, to playfully tease James.