Does feeding on someone kill them?

I really want to become a vampire but dont want to run out of NPCS.

Also how often do i need to feed? Is it game time related or dependant on what Im doing e.g. standing around playing with myself for 4 days means less feeding than if i fight a lot?

cheers

No. There is no adverse effect for the person who gets fed on.

Assuming you mean the normal feed-on-sleeping-people thing. There is also a spell you get as a vampire for use in combat which does hurt your target, and could broadly be described as feeding on them.