1) Don't know, but if you mean split it's pretty good. I'd guess it was similar to how a P-90 sounds, although I've never played a P-90.
2) Sort of, I'd say big (well, huge) rather than fat. It sounds sort of more in proportion than what you'd usually call fat? Very smooth, maybe that's why.
3) As far as I'm concerned the cleans I get from my neck pickup are the best sounds I get from my guitar. It's not a classic clean, words I'd use to describe it are brooding, dark, big again, sort of solemn. Perfect for the sort of clean work you get in metal songs, but not so well suited to country.
Are you familiar with the carcass album heartwork? The lead tone on there is very much what I think of as the natural warpig neck sound.