You should be fine with it outside your coat, just remember to make sure all the ends of the straps are tied up- you wouldn't want one getting caught on the chairlift somehow.
Besides an insulated hose, the best thing you can to do to keep the water from freezing is to blow air into the tube after you're done drinking. This will force the water back into the bladder, and out of the hose. As far as learning back on it on the chair lift, as long as you get the excess air out of the bladder, it is very unlikely to pop.
I've skied with mine in Vermont when it was -5F without windchill and only had trouble once because there was still some water remaining in the mouthpiece. After some time warming up in the lodge it was fine.
This year I picked up some sugar-less flavor tablets from Camelbak during a sale. I'd like to say it was to put more particles into solution to depress the freezing point but I hate the taste of tap water that is not my own . If you want to put anything besides water in it just be sure to wash it out really well afterwards and hang it upside down to dry (with the mouth piece removed). It is very easy for mold to grow in there- and it's a pain to get out.
I'm sure my Camelbak has more than paid for itself by now.. I usually throw a few protein bars in it for lunch and avoid the overpriced resort food.
Edited by sillie - 12/9/11 at 4:57pm