Creature lifespans

[Salocin]

They were like all trolls, they turned to stone if exposed to sunlight. The only difference was that if Sauron's will was on them they didn't.

I dont know if you can corrupt a Fea

Well you certainly don't hear of the Fea of the corrupted elves going to the Hall of Mandos to be with the other elves.

the body may not be totally immortal, but neither are the bodies of elves

They can only die by grief or slaying which, while it is not true immortality, it is certainly more than what the orcs have.