As far as question (1) goes, I do not think that you can find out how many more seasons are left active on a treaty.
As for question (2), there is no way in the game to break a treaty that I know of. I recall seeing others say that there is no way for a player to break a treaty early to prevent players from abusing the diplomacy system (i.e., making peace with an enemy so that you can move your armies into better positions and then turning around and breaking the treaty as soon as your armies are ready).
