It depends on management practices. If the coop and run are stationary they will tear up the grass pretty quickly, so it may be best to put down 12 - 24 inches of wood chips (a carbonaceous diaper) to soak up the nitrogenous waste and avoid a mud pit...If they are fed weeds and kitchen scraps and have compost piles to turn and stuff to keep them occupied, you may fit 12 - 19 birds in there comfortably, depending on the size chicken. If you want them to be more hands off, stocking less birds will cause less problems (in so many ways).
With the tractor, you could raise 14 meat birds in there if you are moving them every day. In my experience I never had as consistent laying in a tractor as I did a stationary coop. I think the hens feel safer when their home isn't running around on them, and I have never been satisfied with layers in a tractor. I keep my layers in the barn at night and they run around during the day, and just use the tractor for meat birds.