They need game bird starter crumbles. Finely shredded grass, lettuce, spinach floated on water. I also puree spinach, lettuce, grass and yogurt for mine.
They need a water container deep enough to dunk their nostrils to clean them out. Chick waterers and feeders don't work well with the type of beak they have.
They do not need water to swim in. As you are taking them from their mother they will not produce oils to protect themselves. Unlimited access to water to play in can lead to accidental deaths. They are babies and tire very easily and can drown in a few inches of water. Wait a week or two and let them swim in your sink with some warm water while you supervise. then take them out and into a dry warm brooder.
When they are 4 or so weeks old you can start letting them have access to small shallow pool of water but make sure they have steps in and out so they don't get stuck in the pool and end up drowning.
Also ducks poop and mate in the water. It will get gross fairly fast.
Be warned they are super messy. When I say messy think of the worst wet poop mess you have ever seen. Multiply it by 1000 and you might get near to how messy they are.
Don't be surprised if they don't like to be cuddled or held. Ducks don't make freinds with humans the same as geese or chickens might. Just the ducks letting you be near them is a success as they get older. They may even become more aloof as they mature and show no interested in interacting with you for more than a few minutes when you go out to feed and fill waterers and pools.