Ducks are happier when they have space and water.
You can feed ducklings Chick Starter. Make sure you give them plenty of Niacin as they need 3 times as much as chicks. It's water soluable and you can pick it up at
walmart for about $10 a bottle (it'll last you FOREVER). Ducklings need 10 mg of niacin per day. It's best to put 500 MG into 8 gallons of water and give them that, most of it will wind up on the ground but they should be able to get the amount they need. They will not Over Does on vitamins. This is important. If they don't have the amount of niacin they need they will have poor leg development and poor brain development. They will die.
You need to change out their brooder box daily because ducks and ducklings are very messy.
The heater temp seems to depend on the breed. Most will be fine with the typical 95 degrees, drop 5 degrees a week method used for chicks.
Pekins can't tolerate such heat (from my experience) and require lower temperatures.
You can generally put your ducks outside after 5-6 weeks.
Girls QUACK. Boys RACHET. Their voices start to change around 5 weeks. This is the best way to sex them other than venting (which takes practice). Some ducks are quieter than others (Muscovy for example).
Ducks start to lay eggs around 5-6 months old.
Happy ducks are quiet ducks so if yours are making a lot of noise then something is wrong. Ducklings will make lots of noise when they're cold, hungry or thirsty.