Elemental Mastery and CAs

It states that it increases damage of heat and cold spells, but do CAs count still?

Yes it affects CAs as well.

It also affects the Cold based proc on the TSO Melee Stance.

Hmm I never knew that, good to know, though i rarely use my dps spec unless im solo.

Quite ironic considering wardens have almost the single best offensive stance among all the healers If you forget about inquisitors, that's it. And sometimes even against inq's one.