i don't know it for sure, but i expect they work with the same algorithm like the ranking from the NT's.
Does the amount of points you win by matter?
yes, the winner get 75-100% of the points depending on the differential of the points and the ranking pregame(if you a far better in the ranking then your opponent then you had to win with a big margin to get all the points)
I am also assuming that div 2 games are worth more than div 3 games and so on and so forth?
i think this assumption is right