When I'm photographing in cold temps, this is my outfit:
- the same insulated bib-pants I wear for ski-doing
- North Face 3/4 length parka with a hood that has fake fur trim, which helps keep the face warm. I don't usually wear my full face balaclava when aurora watching. It's usually on only for ski-dooing.
- the Sorel boots I wear for ski-doing which are almost knee high and have felt liners. I also enjoy my moosehide mukluks at -40 but for aurora in the dark I go with the boots because of their snow tread
- the glove/mitt combination ... looks like a mitt but the tip of the mitt peels back to reveal my shutter fingertip
- fleece hat in case the hood gets too warm over my head
This same combination is useful for photographing dog sled teams. I can plant myself in the snow anywhere at any temperature and stay warm. Was good for 6 hours at -30 last year.
Now having said that ... one night I photographed aurora in my fleece bathrobe and sheepskin slippers. Had stepped out with the dogs for their bedtime pee and saw an amazing display. Ran for my camera and tripod, and ran out to set up the camera. It was warm enough for me to stay out for 20 minutes in this outfit. And by that time the aurora had receded into the dark again.
For your camera ... batteries drain quickly in the cold so have spares that you keep warm next to your body. For the long exposures needed to capture the aurora, a tripod is essential. A sturdy tripod with insulated or foam hand grips is real nice to have so you don't have to touch the cold metal. If your camera works with a remote shutter release, good. If not, a camera with self-timer works well to ensure the camera is steady when the shutter opens. I use 2-second delay timing on my shots.
My best photography night last winter is shared at
http://suethomas.ca/20121113_NorthernLights.htmlHere's one example:

Note that these lights had disappeared by 8:30 p.m.
Sometimes they are visible for hours, sometimes only for minutes.
One of the best displays of lights I have ever seen was at 2 a.m. in February 2012 while driving to Circle east of Fairbanks.