ZakoHero, I think you are going to do fine. A large coop will be good to start with. I like to arrange mine so that if needed, I can separate ducks with some plastic poultry fence in case there are conflicts, or if someone needs a timeout for any reason.
My ducks have what I call a Day Pen. It is a 10'x16' pen covered top bottom and sides with fence. That's where they are when I am not able to be with them outside. They did not have that the first few weeks they were outside because I was building it!
They can manage in a large coop, with supervised time outside while you develop your duckie infrastructure. I agree with Miss Lydia that long term, giving them sheltered outdoor space is the best thing to do.
On the other hand, people do very well with indoor ducks. Duck Forum members are not unanimous about this, so you need to go with your instincts. Healthy happy ducks are the best feedback I can think of for how your management is doing.
So begin with their coop, make it roomy enough (mine are in their coop quite a bit this week due to very low temperatures, so I am glad we have over 100 sf for 13 ducks. And they are fine.), plan for how you are going to keep bedding dry with water and food in the coop (it can be done), and work out plans for an attached run so they can get some sunshine while you are out.
Storey's Guide recommends 10 sf per duck if they have access to pasture (I think there is some room for interpretation about what that is. Our pasture is a number of large gardens and wooded area, but I go with them to these places). 25 sf per duck without access to pasture.
