I've often wondered about how the ranking points are done also. It can't be just based on wins (I don't have that many of those). My buddy said he thinks it's based on who you're racing against. i.e. higher ranking vs. lower ranking. Could be.
As for setups, I haven't been able to access anyone's in the game. I've just had to start with some of the ones on here and tweak them for my tastes.