Coop and run size. It is generally accepted that you need 4 sq. feet per chicken inside the coop and 10 sq. feet per chicken inside the run. That is open floor space.
You state that your run will be 4 ft. x 12' or 48 square feet, enough for five chickens in a pinch. BUT in your coop is 2 1/2 feet by 7' which is a little over 17 sq. feet, only
enough for four chickens. I would error on the side of caution and say four chickens would be the max you should put in there especially since they will be
not free range at all. Crowded chickens are unhappy chickens. Just like humans.