Your location makes a BIG difference.
1. I shut off my diffuser in NW OH a week-ago. Neighbors shut of theirs as much as 3 weeks ago. In the north during November, nature mixes your pond naturally, at this time, usually, you do not need to help her much if at all.
2. Since you will be ice skating - sleding on the pond snow removal will facilitate oxygen production and you should be in good shape for DO all winter.
3. Algae control with copper will not have a lot of affect in this cold water. Since your pond is small, I would remove (lake-rake/net) as much as possible before freeze-up. The remaining algae if it gets sunlight will produce some oxygen under the ice. So make sure you remove some snow around the edges in shallower water. Since the algae bloomed this fall it is what I call a cold water form (could be one or several cold tolerant species). Some limited growth may occur under the ice. It will rebloom again, based on nutrient supply, in early spring when the ice goes off and water is very clear.
