If you do get ducks, get more then one, three is best. They can live with chickens, but I would recommend nipple waterers for your chickens, and that way the ducks can't get the hen's water dirty. Ducks don't NEED a pond, but a few slightly deeper/larger dishes will work well. All that they really need is a dish deep enough for them to clear their nostrils.
It is a controversial topic among duck keepers, but ducks can in fact eat chicken/layer pellets, with no issues.
Will add more later, have got somewhere to go right now.