It is an elementary practice for concentration. It can be done but like anything, an excess of it, can be harmful.

Go by your seeking and aspiration. It is better to hear and read what you want to know. In general, I would suggest Glimpses of

Yes, ghosts are generally disembodied vital entities thrown in the atmosphere after death.

As far as I know he was going through a very difficult phase of his life, having lost his son and separation from his wife.