A 684 Ask your DM.

The feat specifies that in the round after breathing, Clinging Breath causes half the original damage. It also says that you can apply the metabreath feat multiple times for multiple rounds of effect. The feat fails to specify what the damage is in those additional rounds, so that's going to have to be resolved by each individual DM.

A 685 Yes.

From page 5 of ToB:
Stance: A stance is a special type of maneuver. Each stance is a particular fighting pose that grants a martial adept special benefits and options. For example, the Tiger Claw discipline teaches stances that allow the user to unlock her feral, animalistic nature. Unlike other maneuvers, most stances can remain in effect for an indefinite time.