Ducks... raised quite a few. Love duckies, don't love the mess.
The most important thing in my mind when raising ducklings is to keep your sanity. I purchase puppy training pads or adult chux - something that's absorbent and has a plastic backing to keep it from soaking all the way through. I put them overtop the shavings in the brooder, and usually overlap 2 pads so there's a wide area of pad in the splash zone.
The water goes in the middle of the pad layer. When they're real little (I raise pekins so they're real little maybe 3 days) I just take the base of a small chick waterer or feeder and fill it with about a half an inch of water. Change it a few times a day and change the pads once to twice a day, when it gets soaked.
As far as food goes, I put a small tray out near the water (again I use the small bottom part of a round chick feeder, without the top slotted portion on it). If it gets super soaked they won't be able to pick it up well with their bills. Again, I have giant ducks, so I don't keep them on crumbles long. After a few days I go to the 16% layer pellets. It's cleaner than the crumbles, and less protein. I do not care much about the extra calcium. The higher protein is more detrimental to ducks, in my opinion. If they grow too fast they get some weird angel wing thing. So I move them to low protein ASAP, which for them at this house means layer pellets.
They like snacks, too. I get a few bags of frozen peas. I do get some dried mealworms, but only to give them a few out of my hand to get them friendly. Meal worms are very high in protein. You can also rip up some lettuce, they'll love you for it and poop nice green poops for you on their diaper. And with the frozen peas, I don't thaw them. I just plop them down in their changed water, and they play with them and eat them frozen. I don't get it, but they seem to like them that way.
As far as heat, they don't need near as much after they hatch as chicks do. In fact, most of my ducklings are raised without heat and without a mom. Some people will tell you not to let them get soaked, that they don't have oil from the mom and they'll die of hypothermia. I've not found truth in that. However, again I raise pekins, not something small and fragile like calls. They get wet, love it, and then spend a half hour wringing their fuzz out, then nap. I am conscious of the ambient temperature, and ensure they won't freeze to death, but even if I add heat (if I hatch here in early spring or winter) they only get an 80 watt bulb.
As they get older (again with pekins it's just a few days before they start to get gigantic) I'll put bigger and bigger pans of water in there for them to enjoy, along with their diaper. They really like my 8x8 glass pyrex. I will also pick them up and deposit them in a full (cold) tub upstairs for 30 minutes or so while I change the diaper and scrape out the wet shavings around the edges of the diaper (because they'll dig with their bill and wet the shavings down there). They don't like to be touched, held or carried, but they love that tub.
When they are older they go to a bigger brooder where I have a small cat litter box (maybe 6x8 inches?) that I dig down into the shavings, put a diaper between the shavings and the litter box, and then put a brick on top for their step.
They can go outside much earlier than chicks can, at least pekins can.
Hope this helps.
Silly boy! He's knows I have all the roosters here. They start about 2:50am...at the very first light showing in the north.
