You'll get so many more responses if you have a mod move this to the duck section, but I'll help as best I can
Before you bring your ducklings home, make sure you have a nice warm brooder waiting for them. You'll want to make sure you pick up a game bird or waterfowl feed, corn and chicken feed don't contain the necessary vitamins and minerals to keep waterfowl in top shape. For example, they need niacin or they can develop twisted legs and feet. You'll also want to make sure their drinker is deep enough for them to clean their sinuses in. They dabble in the mud and dirt (yes, even in the brooder. Don't have mud or dirt? Don't worry, they'll manage to make some).
Be very careful letting your duckling swim, they can drown! Yes, seriously, ducks can drown. No unsupervised swim time until they have their adult feathers. A momma suck supplies her duckling with oil, they get it when they rub up against her feathers. That oil makes them waterproof. Without it, they become water logged and the worst happens. Unless you can supply the necessary oils, keep a watchful eye.
Oh, and we may have differing opinions as far as pekins being the best breed. Personally I prefer calls
Duck are cute and very funny, I think you'll enjoy them! Good luck!