Do yourself a favor and grab a copy of Storey's Guide to Ducks. It is filled with absolutely wonderful information.
You don't need a coop, per se, but you do need some kind of shed or shelter for them - they'll need a dry place to eat, brood, sleep and the protection offered. Ours as adults prefer to nest under low-hanging trees and bushes, but a few gals used our brooder shed for nesting this year. Think 4 square feet or so per duck in housing. They are incredibly messy, so whatever you use in the shelter, make sure it's cheap and plentiful - we use orchard hay since it's really cheap here.
Ducks do well in cold weather, but they do need a way to get dry. You'll have to make sure you have a way to keep their water from freezing, in winter we use several livestock watering bins with the attendant water heater coils. They work great and are fairly cheap. Some folks like to use metal waterers set atop homemade heaters, those seem to work great, too!
Waterers need to be at least 4 inches deep, as they need to cover their entire beak, almost their entire head to clear their nostrils when they drink. This will dirty the water and waterers, so they need daily clean outs. Chicken waterers do not work well for this reason, but a few cat litter bins bought cheaply work very well and are cheaper than livestock watering bins.
You'll need a secure pen and get them trained to go into it, most folks tend to feed only within the pen which works great to train them. The shelter should be either inside the pen or accessible via the pen. Mine is set next to it with a door in between.
The layer ducks should be fed around 18% protein feed, which is a big high for meat ducks though it won't do them any harm. You don't need to separate the meat vs egg ducks until you're getting close to processing. At that point, you should remove the meat ducks and put them on finisher feed for the last 3 - 6 weeks.
Anything else I can help with?
