I don’t think the file came from the basement, in the sense that he went down there, picked it up, and carried it with him to the church where he meets Cole. He had a file because he thought he was meeting with a new client, and when he does that, he has their file with him. It’s the same reason he’s wearing pants throughout the movie. He’s not wearing the ghost of the trousers he wore when he was shot, he just “has” the accoutrements that he thinks are appropriate to the situation.
Because Crowe needs an excuse, in his own mind, to explain why he’s hanging around Cole all the time. It appears that, much like ghosts can create “objects” (such as pants and file folders) to match their preconceptions about what they look like, they also create memories for themselves to paper over gaps in their own recollections.
This is not something that’s entirely without precedent in actual humans - Crowe (like most of the ghosts in the movie) is basically in denial over a traumatic event in his past. People suffering from serious denial can be astonishingly good at not noticing things that are starring them in the face. Crowe takes it to olympic levels in this movie, but presumably, spirits (not being hampered by a physical biology) are more prone to this than the living.
Subconsciously, Crowe knows he’s dead. His subconscious is telling him, “You had a hole blown in your torso a year ago, and now you’re dead.” His conscious mind, unwilling to accept that, interprets this as his old bullet wound acting up.
I suspect he doesn’t realize that he doesn’t do any of those things any more. Since he never feels hungry any more, he’s assuming, in the back of his head, that he must have eaten recently. If you quizzed him on it, he wouldn’t be able to recall specifics - and, like most people suffering from denial, would probably get angry at being forced to confront uncomfortable truths about his situation.
Which, incidentally, is probably why Cole never comes out and tells Crowe that he’s a ghost. He’s tried it before, and it usually just makes the ghost angry.
Psychologists treat illness of the mind. That doesn’t make them immune to those illnesses, any more than being a cardiologist makes you immune to heart disease.
In no way do I see the film as mocking psychiatrists. Crowe is explicitly presented as someone who is very good at helping people with emotional problems, and at the end of the film, he has successfully used his psychological training to help Cole integrate into society. And Cole has, essentially, done the same thing for Crowe. Both characters are suffering from the effects of a psychological trauma. By seeing how Crowe is helping him to resolve his own trauma, Cole is able to help Crowe resolve his. The film is overwhelmingly positive towards the idea of psychiatry and psychiatrists in general.
Shyamalan didn’t really invent any rules for this movie. Everything about how ghosts behave in this movie is taken directly from real world folklore. What Shyamalan did that was new was to tell the story from the POV of the ghost.