Will the pen be around the pond? Wood ducks can and will escape. It needs to be fully enclosed and predator proof.
How big around will the pond be? They really don't need a huge pond. I have a 10x14 pond in my pen, it's about a foot deep. It has a large pond liner in it. I have 21 ducks and in there and it's plenty big. Concrete ponds are also good but I've never personally had one.
The pen size will depend on how many wood ducks you want.
They can not ever be in with domestic ducks, no. Call ducks are the only kind of domestic duck that can sometimes be in with the ornamentals. Wood ducks are really very small. I can fit my hands all the way around their body and I have small hands. Bigger ducks will hurt them, even if they just step on them.
The ducklings can be very difficult to get eating. They're much more difficult to brood than domestics. They need to be kept EXTREMELY clean, the brooder should be completely cleaned at least twice a day.
The hens should if they're kept well and not stressed out. Usually they'll breed their first year, but some won't. Each hen lays around a dozen eggs per year. That's why most breeders do not sell ducklings or eggs. Any eggs you may find available will cost the same as buying the birds themselves, since so few eggs are laid. The hens should not hatch the eggs themselves, it's difficult to allow the parents to rear ducklings because there are so many ways they can hurt themselves. Brooding them yourself is usually much safer.
I don't know what I would sell any for yet, we'll just have to see how they do and if both pairs make it through the winter ok.
