Well, my geese try to go after my chickens, but there is a fence in between them. The geese actually grab the fence in their mouth and shake it. They are clearly doing it because they are fussing at the chickens for some unknown reason.
So, unless someone has experience with housing them together, I would think there would be a high risk of the geese killing or damaging the chickens. Maybe you should ask on one of the geese threads here on BYC, because I really don't know.
As to water freezing, are you in Fairbanks?
I do get perpetual ice water freezing issues..... But mostly because I am always having power outages. Also, I am up high enough, and with a bunch of wind, and that greatly increases the freezing potential. I have actually already had some frozen water these past few days *sigh*
But, I use a stock tank deicer that is safe to put directly on rubber. I then put that in one of those black rubber horse feed pans. The stock tank deicer is strong enough to thaw itself out of a solid block of ice, which happens frequently.
I have to be super careful about the water and humidity issues, because being close to the coast I have pretty high humidity just in general.