Yes, ghosts do exists, characters may hear whispered rumors that such entities frequent the currently inaccessible Land of Rot. That is all that would be available on ghosts at this time as none are found in the currently opened areas but you never know what the future holds!

No, due to the conflicting of the spirits now being a sort of separate entity from the living magic would not be able to communicate. What would count as a person even for magic standards would be any creature who is breathing, with a heartbeat, and capable of thought and speech.