Special considerations for a new duck house

So I have researched it. I want to build a playhouse, basically, for 2-3 females and 1 drake, likely muscovie, in the spring. I know this is necessary:

Ventilated
Predator proof
Swimming pool
Straw or hay for bedding
Fresh drinking water


I know they don't need roosts like my chickens.
I know I want it to be easy to clean.

I'm wondering about draining the kiddie pool I have. Should I raise it off the ground a bit, add a drain hole and drain with PVC pipe attached underneath or how is that best done? Just pick it up and dump it out weekly?

Is a dog house type thing better except one with a removable or hinged top?

I lock my chickens in their coop at night and the ducks will be the same. Keeps them safer. My main predators are my own dogs. They are doing well with the chickens when they free range each day. They keep most other predators at bay, like raccoons and coyotes. I plan on 16x16 pen with either welded wire or possibly hardware cloth on the bottom. With the play house accessible from both inside and outside the pen. I want to put it near my chicken coop so I can use part of it for food storage for both ducks and chickens. It is planned as a playhouse because I have easy access to easy diy plans that I can do. Winging it does not work for me. I plan on using one side of the chicken run as one wall of the duck run. We live where summer is more of a concern than winter so it will be in the shade.

 

Is there anything I'm missing? Anything that would be a good idea to include based on your experience?

My understanding is that they won't fly out so a 48-60" fence should be fine with no top?

 

Also is it muscovies I want? I live where it gets 100-105 on the hottest days in the summer. It can freeze in the winter but not for long usually and we rarely get snow.

I want eggs. They don't have to be awesome layers but eggs I do want.

I like friendly birds. And am looking forward to considering them pets as well as egg producers

2-3 females and 1 male is a good way to start right?

I could build a pen that can inhibit ducks from escaping when I am not here but would prefer ducks that just don't fly much nor do they have the desire to escape. They will free range with my chickens.

I do expect them to go broody and hatch some eggs at some point.

The local feed store has ducks in the spring but I don't recall it saying what kind they were. I could order from a hatchery to get the ducks that best fit my needs.