reanimation

[parcelt]

I just found out playing Abysia that my prophet can reanimate, and I am trying to figure out the details. So far, I am only running into more questions:
My prophet gets a choice to reanimate ghouls, soulless and undead. Which are best?
How does the number of corpses in a province affect reanimation? Does it have any effect on the province (does it increase unrest or something)? Is it bad to just leave corpses sitting in province?