I raised laying hens back in high school. It was normal to get 8-10 eggs/day out of 8 hens. At least one double yolk egg per week too. Feed them well and the eggs wont fit in a jumbo carton.
We are allowed to have up to 3 hens in our neighborhood (its actually in the City codes). So we are thinking about it too.
Google small chicken coops and you will find some ideas. Also, farm supply stores, even some Ace Hardware stores, have rabbit hutches that might work.
In regards to smell, if you are in a neighborhood, like we are, you will have to clean the coop every week, no taking a break. Compost the results or put it in the trash can.