I have runners, khakis and a cross between the two. I have them in separate flocks - garden and fields. The garden ones are pure runners, although do have some ducklings which are a cross. I keep them in the same house as my chickens, and a goose, but they are free range throughout the day, and put them away at night. They do have access to a bin lid full of water, which they do seem to enjoy having a little paddle. They get mixed corn each end of the day, but in winter, they do have unlimited access to it.
My field flock come and go as they please, and do spend a large amount of time on the stream running through the field. They don't have a shelter, and tbh, during the summer, we don't see them a great deal as they spent most of their time up the field. Come winter, they will come down to feed and usually sleep in the duck pen. They do tend to come down either in the morning, or evening for some mixed corn - which I chuck for the turkeys anyway.
When we do need them to be put inside, we do "herd" them and they are all pretty good, but do find the runners a bit flighty, although that could well just be my flock.
They can make a mess, so be aware, especially where the water is. I don't like keeping too many drakes together because when the breeding season starts, they do fight over the ducks. I've never had a flock of all drakes though.
I've found what works with my mixed flock and I'm sure they don't read the rule book cos they do everything wrong!
Helen