Trackingskills and subraces (oh my!)

OK, it's a two-for-one question special:

I just wondered if one increases her tracking (as in identifying tracks) skill by using it, or is it simply determined by spot/search skill level? Basically I want to know if it's worth identifying tracks that I've already come across but have popped up again on a subsequent trip thru an area.

Also, is there a place to read up on some of the background lore about any of the sub-races? Just a sort of "This is where they come from and what they're generally like" etc kind of stuff? I'd like to try some of them (like the sea elves or triton kin) eventually, but wondered if there was any way to put them into context, as it were.