Maybe it (cold) could work like White Phosphorous? Take the health away from troops but doesn't kill the members.
Excellent idea! I would support this actually.
Also vision block is cool, deep snow is a bit annoying, make squads move just a bit faster in that (but not the normal speed) ?
No, it's just about the retreating squads. There is the real problem because if you enter in deep snow with your units, that was YOUR decision. The retreat path it's not your decision anymore. So as someone said already, when it comes to retreating squads, let's make it like in fences case: retreating squad should automaticaly go around that deep snow area.