Cold weather ops:
Remoting the battery by using an extention cable and keeping the battery under your coat and against your body will do wonders for your shooting time. You can us a rain jacket like the heavy ones made by Porta-Brace. The old padded 16mm camera barneys to kill sound of noisy film cameras of old worked good for temp insulation too. We used to put chemical hand warmers under them near the motors to keep things working. I've seen a camping heater hanging under the tripod in at least one extreme cold situation when wind was low.
For small video cam, when you go inside after being in extreme cold, if you put the cam in a plastic bag first or in a moisture sealed case, the condensation will form on the bag instead of on (and inside) the camera.
At very least, make sure your lens cap is on when going from cold to warm.
Oh yea, have plenty of lens cleaning tissue handy to wipe off lens condensation when it's unavoidable. Even if the camera will run, shots are no good if you can't get the lens cleared off.
Here's another one: for viewfinder fogging, put your mouth up to the eyepiece as if it were a tuba mouthpiece and suck in as hard as you can, drawing dry air over the view lens. It usually works.
Try to keep your hands warm or you can't work. I really liked gloves with no finger tips. If you need full coverage, goat skin work gloves are very pliable so you can feel the controls. Also quite tough.
Have done some shooting in Russia in the winter. I liked having a chemical warmer pack in ea. pocket. Felt great between shots.