Your coop is large enough (just barely) for 12 chickens; the recommended minimum is 4sq. ft. per bird, but you need more run space. The recommended run minimum is 10 sq. ft. per chicken, which means for 12 chickens you need a run of at least 120 sq. ft. (more would be better). Overcrowding can quickly lead to aggression, feather plucking, and even cannibalism. Golden Comets are great chickens; one of a number of labels that Red Sex Links are sold under and they are egg laying machines. Good luck with your flock.