Loss can bring on many emotions and changes in behavior, even years after the death. I would suggest getting his son into therapy rather than worrying about ghosts.
Absolutely not. There can be psychological abuse, emotional abuse, etc. There are all kinds of variations. This is another component that can make it so difficult for someone to spot...
Get away from them and contact a priest to do an exorcism. Peacefully moving around an area, a white patch on a picture, and a few bumps in the night...
If the couple is still married, then no - marriage laws require that they both own the home. If they have divorced, then yes, the deed can be quit-claimed to...
Talk to the bishop. The hardest part is setting the appointment and taking the first step into his office. But bishops are there to love and support you.