First off, an answer to your question: Yes, everybody should have ducks!!
But seriously, I already had chickens when I got my first runner ducks. I have never had a problem with the drakes wanting to breed with chickens (they're too busy romancing their own girls). Also, runners are on the small side. Most of my chickens are not and may just intimidate their would-be suitors.
However, I house them separately. Ducks are incredibly messy; their love of water means spills everywhere and their droppings can be overwhelming. It's too much moisture for chickens.
Good news: Because moisture levels aren't as troublesome for ducks, their housing can be more simple. Mine spend their nights in what is essentially a giant wooden-framed, rectangular box (3 foot by 10 foot) wrapped in hardware cloth. It's elevated about a foot off the ground to allow excess water to drain out. Half the floor is covered with a fake grass rug (that's regularly replaced because it's easier than cleaning it!); the other half with vinyl flooring that has drainage holes punched into it.
For shelter, the top is covered in plywood, and in the winter, I hang laminated wood panels across the sides and one end. Winters here are often brutal, and chickens would likely die in this set-up. But the ducks do fine. My goofballs often leave their housing and lie in the snow, even during raging storms!