I start my ducklings on moistened Flock Raiser shortly after hatching. When I spoke with Dave Holderread last week he said that the Purina Flock Raiser was the most complete of the feeds but he orders his own special blend for his ducks and has it delivered. I actually feed Flock Raiser to everything except chicks, which start on medicated Chick Starter before they switch over to Flock Raiser with everyone else. If you use the right feed for your ducks, you won't have to over compensate with vitamins.
Once ducklings are feathered they can go outside, assuming you have acclimated them off heat as they are feathering out. Ducklings feather from the bottom up instead of from the top down like chicks so ducklings get their wing feathers last while chicks get them first. Once the ducklings are outside, they are much easier to keep clean but they will get their water dirty. Someone once told me that ducks make mud but really dirt and water make mud and the ducks just like to mix the two together.
I have found that ducks bred for meat, with the exception of Muscovies, are not the best pet ducks. They are bred to live a short life and then die. The "ornamental" ducks seem to make better pets and my favorites are the bantams bred to be "functional" ducks and not "toy" ducks. They earn their keep around here with their foraging and egg laying.