slight spoiler warning since i dont know how to make those cool little black bars over my text.
there is also a point on korban when you come close to Marca Ragnos's tomb that triggers one of Kreia's little "mind conversations" where she tells you that Ragnos ruled the sith empire for over a century. that in and of itself is evidence that force use weather light or dark has a tendancy to prolong normal human lifespan. then again Ragnos was also a "half-breed" half of what I cant remember but I do remember mention of him being half bread of something.