Mpavlik22, 99.95% chance the yeast in the bottom of the primary are not dead, just dormant/sleeping... Unless you add something to actually KILL the yeast that is...
I've dry hopped in primary, and will be doing so again shortly.
Since I'm not adding fruit, or sugars that benefit from getting off the yeast cake, I do most of my additions in primary. I will age in another vessel, as I already mentioned, WHEN it makes sense. But, IMO, it makes no sense to do it for ALL batches.
As Mpavlik22 mentioned, there's still a good amount of controversy over if/when to rack to another vessel... Although the big brains of brewing are siding (more and more) to it not being necessary, or even a good thing. 10-20 years ago, when home brewing was still in it's infancy, it seemed to make sense. But those are the dark ages of home brewing... We've passed through the renaissance age, and are approaching the next epoch in home brewing...