I think Pekins are the only ducks that are legal to own in Florida? But there are tons of Muscovy that need safe homes. They really do make great ducks for a homestead.
They could probably free range fine with the chickens as long as the chickens accept them, we have a member here who is dealing with an awful wound some of her chickens did to her duck, so sometimes chickens and ducks don't do well together. My chickens and ducks are in a half acre together...