Tournament games aren't marked as created by the tournament creator. Instead, they get a line in the settings that says what tournament they're part of. Players can click that to see who made the tournament.
Googling "python elo" finds a few promising projects.
"Python Implementation of the TrueSkill, Glicko and Elo Ranking Algorithms" : https://github.com/McLeopold/PythonSkills
TrueSkill or Elo would probably work well for you. I know TrueSkill even handles teams properly (even when players may play different games on different teams, it will reward everyone correctly).
Edited 9/11/2013 21:54:23