Good luck! We have seven silver Appleyard ducks, and it's been quite chilly here (we have not seen double digits F in well over a week, and nights are falling to -10 F and colder). Our ducks have been eating less of their regular food ever since this cold snap started. We started offering some cracked corn, which they plow through, and we also feed them a soup twice a day (warm water with a mix of peas, carrots, raisins, green beans, oats, etc.). It took a while to get them into the soup, but now most of them eat it with gusto. They remain absolute fiends for meal worms, which they get as a garnish in their soup and then at the end of morning chores and about 20 minutes before we lock them in for the night. We have a similar water set-up as Miss Lydia (actually I think we copied her design pretty much exactly ;-)), and they do all get pretty wet first thing in the morning when we let them out of the duckhouse. We're a little worried about one of our ducks who gets really wet, but we're just watching closely.
...speaking of watching, we have wi-fi cameras in our run and duckhose, and those have given us a great deal of comfort during these cold temps. We also have a wireless thermometer in the duckhouse that shows us temp and humidity. We're probably a little over the top in terms of being protective duck parents, but it sure does make us sleep better when we can check on them whenever we want. ;-)
Keep us posted!