I believe the best you can get (unless the ? stats are actually random, not predetermined) on stats is 250 Charm, 270 Int and Agi, and 300 Dex. Someone correct me if I'm wrong, and if anyone managed to max out any stat but Dex, it's probably because ? stats are random.
Evilish, I hope you realize the game autosaves... If you refresh you start at the beginning of the room, and I believe you keep any XP earned in the room as well.
Fantastic game. Very fun and addicting. I hope you can make the poison tower attack only non-poisoned enemies. This is a huge problem for me, if you could do this, or have the ability to choose who the towers attack (such as click on a tower, then an enemy, and that chooses who it attack) then problem solved. Usually when 10-20 enemies come from the enemy "base" only 2-3 get poisoned and it could be 10-15 of them because it shoots at a pretty fast fire rate, this would make it more effective immensely, and would be a lovely addition to the game.