The Display Stats tool tells how long you have been playing based on what Mobsters servers send back to SuMob via request, so whatever time it shows is correct. Yes it is based on that specific toon/saved game.
As for the Stats Level "Stats Level is 3 (56.12% Good - 43.88% Bad)".
Essentially, it takes all your stats that are related to each other, and adds them together, and finds out what percentage is good, then it adds all the percentages together, and divides them by the number of ratings calculated to come up with a certain percentage, then gives you a level of 1-5 based on the percentage of good.
For instance, if you have 8000 wins, and 2000 losses, that's 10,000 total fights, 8000/10000 = 0.8 (aka 80%), so 80% wins, 20% losses.... the same general idea is applied to a bunch of other stats to get a final value.... Many petty things are included in the percentages to give a more accurate level.
I will soon be integrating the Player Rankings tool, which also ranks you against other players on your level, although if you are using the Stats tool for Sorority Life or Mobsters 2, I don't have information on enough toons for those games to enable that feature. I can potentially do it for MySpace Sorority Life, but due to FaceBook's insanely sparse ID numbers, I don't know if I can do the Facebook games.