There are a number of ways to accomplish this, here's one. Set your "Points for Playing" to:

10 + (nh*5) + if(r=1, 50, 0) + if(r=2, 40, 0) + if(r=3, 30, 0) + if(r=4, 25, 0) + if(r=5, 20, 0) + if(r=6, 15, 0) + if(r=7, 10) + if(r=8, 5, 0)

For the second session, add:

+ (na * -25)

You'll have to adjust the points manually to add the 10 and -5 points for hitting/being hit by a player with a higher/lower league ranking.