The icy breath is a good idea, but will take a lot of work to make it look right. As is, it kinda sticks out and seems a little 'off'. Like has been said before, the breath will need to be there for bigger breaths and need to match what is being said to the T, otherwise it looks fake.

I also think the breath would only be apparent in the outdoor or Wampa cave settings because of the great decrease in temperature. I envision the rebel base as more of an igloo environment with natural insulation, where it is colder, but not so much that heavy jackets are needed all the time. A lot of characters are in lighter apparel, wear no hats, or have their jackets unzipped. Once acclimated to a slightly cooler, but not frigid, environment, water vapor from breathing is barely perceptible if visible at all.