On number 2, I don't remember the term but there is a concept in Catholicism in which God allows demons to possess innocent people as a test of faith. Unlike sinful people who become possessed through their actions, these innocent people do not risk losing their soul or going to hell. I'm sure that would have applied because trying to communicate with the other side opens one up to possession per their doctrine.
I read about this sort of stuff in this book:
In "The Rite" (the movie), inspired by true events, a priest who performs exorcisms professionally falls into dispair, a demon invades, and he himself needs an exorcism. The movie is based on the book, which is non-fiction, written by the junior priest who is trained by the one who is possessed. I have not read the book, might help:
http://www.amazon.com/The-Rite-Making-Modern-Exorcist/dp/0385522711/
You can read The Rite for examples of the process in action. But basically the psychologist rules out the person having any mental disorders. Depending on the possible demonic activity, the person also might need to get examined by a doctor to make sure there's nothing physically wrong with them.
It's not that the psychologist is finding something in particular. It's that the psychologist doesn't find anything.
This could be a conversation starter with your roommate... If they believe in the supernatural, there could be a chance to talk about some of the unintended consequences of messing with the spirit world. The book below was pretty interesting to me.
https://www.amazon.com/Rite-Making-Modern-Exorcist/dp/0385522711
The Rite, it’s a book about a Catholic Priest who was trained and performed exorcisms: https://www.amazon.com/Rite-Making-Modern-Exorcist/dp/0385522711
If you want to hear an interview with him: https://thedeconstructionists.com/ep-60-father-gary-thomas-deliver-us-from-evil/
I have witnessed a couple of exorcisms, as well as sensed demonic spirits nearby.
A couple years ago I had picked up a book called "The Rite" although written from a Catholic's perspective, it was an interesting book that I just skimmed but my husband actually read. Strangely, my husband had just randomly decided to read the book just a few weeks prior to experiencing a exorcism that we were both involved with. (He said that a couple things helped him. One was that it helps to cast a demon out when identifying what demon it is, calling it out by name. Also, the demon likes to hide and pretend it has been cast out even though it hasn't. This came up in the exorcism we were involved with) The demon was basically possessing a young man because of deep hatred/unforgiveness this man had towards his father. Both my husband and I had no fear in dealing with the demon. We loudly, and strangely in unison said, "Tell us your name!" The demon said it would "never tell us" but then my husband was given insight as to how it was there because of unforgiveness. The demon was eventually cast out, as the young man prayed to forgive his father, after convulsing on the floor and yelling "no" and other blasphemies. We prayed for this man to be filled with the Holy Spirit as well and he left the small group a changed young man. Pretty intense, yet amazing really. I ponder why we don't encounter them more often as I sense many people are more oppressed or possessed than we are aware of. I don't really understand it all that much myself. I have some of my own questions. I wonder why some demons suddenly manifest and other times they just stay hidden? Why can't Christians always just cast out any demon as they encounter them? I have had demons "recognize" me at times while I am out and about. I can just sense a demonic presence but I don't particularly feel like I should do anything about it. But why not, I wonder? Is it because the person needs to be ready for deliverance?
Anyway, here is the book I had mentioned:
https://www.amazon.com/Rite-Making-Modern-Exorcist/dp/0385522711
From a Catholic perspective, I thought The Rite was interesting.