You can look through these stickies to get a whole lot of ideas. The “things you’ve learned” thread can give you all kinds of ideas.
You don’t say where you are. Your climate can play a big part in what your coop should look like. You might want to modify your profile to show your general location. That helps a whole lot when answering a lot of questions.
I suggest you follow the link in my signature to get my thoughts on how big it needs to be. We are all so unique there is no one number on anything that covers all of us. I also suggest you read these, especially the last two if you are not in a really cold environment.
Pat’s Cold Coop (winter design) page:
Pat’s Big Ol' Ventilation Page
Pat’s Big Ol' Mud Page (fixing muddy runs):
In general I find the more room I give them the fewer behavioral problems I have to deal with, the more flexibility I have to deal with issues, and I just don’t have to work as hard. This extra room means in the coop, run, brooder, nests, and on the roosts. Give yourself good access, it’s a lot less frustrating. Be flexible, things will not work out exactly as you plan them.
We all have our favorite breeds. There are a lot of breeds that will suit you, about any of the dual purpose breeds. Not knowing where you live and whether you have a specific need for a cold hardy or heat tolerant breed, I suggest you look through Henderson’s Bred Chart and try to pick one or some that you think you might like. Things to pay attention to are size, you want early maturing, and egg laying. Depending on how you manage them, you might want some that take confinement. Do you want them to go broody? That’s why we have favorite breeds, we have different goals and set-ups.
Henderson’s Breed Chart
Another thought is to get a special from a hatchery where they send you an assortment of different breeds so you can compare them and see which you like better. These assortments are at their discretion, it’s basically whatever breeds they had hatch well that week so they have extras.