Ducks like living with other ducks. They speak the same language and have the same needs. Additionally, there is no guarantee that the duck and your chickens will get along and they may always need separate housing and run space with a fence between them. If you are not prepared to make separate accommodations for the duck, I would not recommend taking it in. To answer your other questions, they can eat the same feed and they can get by without a pond. Please explain to your friend that releasing a domestic species onto a local pond is not a good idea. Pekins cannot fly to escape predators, it can throw of the ecosystem, the duck may or may not have a good food source, the duck will not migrate or "fly south" for the winter, it's illegal, etc. Perhaps you can help you friend find a new home for the duck on the buy/sell/trade section of BYC, place an ad on the local Craigslist, place an ad on a local FB poultry page, put up a sign at the local feed store, etc. While taking this duck in may not be something you can/should do, you can certainly help your friend to do what's right. Good luck.
