In my fourth year of my PhD on schizophrenia and I'm currently writing up my thesis. I'm procrastinating right now so thought I'd do something useful with what I've been studying.
And no, schizophrenia is not multiple personality disorder.
Edit: I have to get dinner and run some errands. I'm really enjoying this so I will definitely get back and answer the rest of the questions.
I remember hearing this about ghosts as well. It makes sense they're related, but in America ghosts are also uniquely malicious and in most cultures they're kind and usually a dead relative or friend.