Some kind of waterproof pants are a necessisity in Antarctica. When we went we wore regular dungarees under our nylon, outer waterproof pants and that was adequate for one of us( me ). The other wore the nylon thermal long johns as well, and that was adequate for her( she gets colder than I ). But you should realize that it's summer there, and it may actually be warmer in Antarctica than it is in Buffalo. When we went( January ), the temperature was in the balmy low 40's, but it was 20 degrees colder back home in NY. We didn't take heavy ski pants, as what we took was more than adequate. Remember to take into consideration how much your luggage weighs.
We concur about keeping dry, particularly your hands. The biggest problem in Antarctica is keeping dry, not necessarily keeping warm, because it really will not be that cold when you go. You'll get colder fast if you get wet. We recommend visiting a tackle shop and purchasing a pair of rubber gloves that surfcasters use, with the inserts. Those gloves have a split forefinger, which is necessary for surfcasters to cast, but even more necessary for you to take pictures. These gloves allow you to keep them on and keep your hands warm and dry and easily manipulate your camera. Those may be better than using kitchen gloves underneath an outer glove, as kitchen gloves will still bulk up your trigger finger, where the surfcaster gloves won't. We were the only ones who had those gloves when we went to Antarctica, and we were the only ones whose hands stayed warm and dry.