Seems like you're doing the basic "one more point than the person before you" method, which in the points for playing box in the game tab, you will want to enter n-r+1
Point for buy-in, you can put in the box, as I do for mine - Mine is also a freezeout (no addon/rebuy).
For overall total, you will need to create a "filter", where you may want to have a season as well. The season will group similar tourneys together, of sorts, so that when you run the stats filter, it will look for tournaments with that season setting. I've attached a sample tourney so you can see what I'm talking about, too, for this. Our league also awards points to the top ten, based upon the number of players that started, so my points for playing box will look very messy.
Is there a better way? Depends. Do you run many tournaments in a season? How volatile do you want rankings? (how much do you want a bad night to hurt a player's ranking) I'm sure there are other questions that you could ask yourself, and everyone would answer them differently. What we have for our league is what works for us - depending on the season, an average of 25-45 players each Tuesday.
Again, below is a tournament to show how my tournament settings are. It's from the first week of the current season.