alternator- fixable?

[wanna986]

I just finished diagnosing my red battery/generator light which started to glow yesterday. The alternator is not charging the battery.

It turns out that upon engine shut-down, when the serpentine belt stops, the alternator impeller (?) keeps spinning and then, a second or two later, decides to whine/screech to a halt.

Three questions:
Which part of the alternator has failed?
Is the failed part consistent with not providing a charge?
Can I remove and rebuild on my own?

Thanks. Hoping to get back on the road sooner rather than later...