Here's a formula for your points:
switch(r, 1, 15, 2, 12, 3, 10, 4, 7, 5, 6, 6, 5, 7, 4, 8, 3, 9, 2, 10, 1)
To collect stats, you just need to save each tournament, then use the Stats tab to compute them. The number of final tables is computed for you, as well as the number of 1st place, 2nd place, and 3rd place finishes.
For your "non-league points" tournaments, I guess you can just not assign a Points for Playing formula for that tournament. They'll still be included in the stats, but obviously players won't be awarded points for those tournaments. There are other ways to do this if you have more detailed requirements.