Ducks prefer to sleep on or near their pond. They may not be on it all the time, but the will be near it all the time. Make sure they associate food with you so they will come to you and call to you when they see you. Predators could be a problem with all that (wonderful) space.
Our ducks would eat or up root anything growing in the pond. Their favorites are lillies and Iris. They prefer tender new shoots so if you can protect the pots until the plants are older they may make it. We put some hardware cloth type of wiring aound the pots. Let's water in and keeps duck...
We have a large back yard Koi pond that the fish share with 4 bantam sized ducks (Call Ducks). We only clip wings when we first get them. They can all fly now but don't, except low across the pond. They are not cuddly, but they come when I call them, they love nightcrawlers and eat them out of...