Question: Winter Terrain

[Warmonger]

Is there a chance AFVs will become immobilized in a frozen swamp much like in an unfrozen swamp? I know from personal experience that the ice in frozen swamps isn't strong due to all the plant material and I wonder if the game reflects this.

Same question for frozen streams since ice isn't as thick where the water is moving.

Finally, I haven't been able to figure out if sighting through trees is improved due to a lack of leaves.