Thank you! I just read through that.I don't know anything about ponds. You might ask on the duck forum. Also, if you add your general location to your profile people can give better targeted advice.
Here's a great article on cold weather poultry-keeping: https://www.backyardchickens.com/articles/cold-weather-poultry-housing-and-care.72010/
At those temps (below 0F) you can NOT let them bathe.Our winters are cold, we usually have snow from the end of October through late April, and frequently dip into the negatives. It is not uncommon to get down to -30 or so. We also get a lot of snow.
I really am not fond of heat lamps. A cold gust of air can make them break sending hot shards of glass all through your bedding.My shed is not insulated or heated. I plan on trying to run a heat lamp or two when it gets colder, and I think that will help.
I thought about insulating the smallest inside pen.
I also am thinking about drilling some small holes in the floor for drainage, putting down a few of those rubber stall mats with the holes in them,
.There is a big net stretched over the top of the pen,