4 square foot per chicken inside the coop. 10 square feet per chicken inside the run. a little bigger is always better.8 foot x 8 foot coop would do nicely and the run 10 foot by 10 foot would work well i think.
I raise heavy breeds and have 2 rows of nest boxes stacked. Lowest row is 3 feet off the floor and 2nd row is 4 foot high. Initially, I had built them, starting at 18" off the floor and found that NO chickens would lay in the bottom boxes. I then raised them all and now find that most of the chickens lay in the top boxes (4 foot high).
I found that roosts stacked in a ladder fashion work well if you raise various breeds, as an earlier poster mentioned, some breeds need to or prefer to roost lower than others. I'd say most, if not all of my Rhode Island Reds are currently roosting on the 2 top roosts that are 4 1/2 foot high.