I agree with previous posters that the only sure fire way to keep the ducks out of the pond would be to put up a fence. I don't know if offering them a pond in the yard would be enough to get them to stay.
You won't really know if the ducks and chicken will get along until you try. Mine get along just fine and they weren't raised together.
The smallest domestic breeds would be Call ducks and Mallards. They are about 2.5 pounds. Calls were breed to be noisy; that may or may not be a problem for you. You aren't going to get a big egg from a small duck and neither breed will give you a lot of eggs. Maybe 80 a year with a Call if you are lucky and 60-120 for a Mallard.
Runners are defiantly an option if you are looking for color. They come in a several different colors. They are considered a light breed at about 3 to 4 pounds. They're said to be decent layers, 100-120 a year. They do have a very distinctive look.
I personally don't like the look of Muscovies. I just don't find the carnucles attractive. But, like I said, it's a personal preference. Muscovies aren't super heavy layers and are said to go broody very easily. They are suppose to be great mothers.
The reason they suggest lighter breeds as garden ducks is because they are usually better at getting the majority of their food from foraging. But that doesn't mean you have to get really small ducks. You just want to go for those breed more for eggs than meat because the meat breeds need more food to gain and maintain weight. Some breeds that are know to be great foragers are Khaki Campbell, Magpie, Ancona, Welsh Harlequin, Runners, and Swedish. Some that are good foragers are Rouen, Cayuga, and Buff. I personally think all these breeds are pretty and some are on my list of wants.
My all time favorite are Welsh Harlequin, which is what I have now. @chickens really drake is a beautiful example of a drake WH. They are also great layers at 150-200 per year. But they are a broody breed which can mess with egg production. Mine don't sit in my lap or anything but they will eat from my hand and often hang out around me when I'm in the yard. They also like to yell at me from the back door, especially when they want mealworms.
