with 12 pullets be prepared for 10 plus eggs per day. 7 days a wk. thats alot of eggs.
you dont need a rooster at all. your hens will lay well with out him. you'd be better off w/o one. if your not breeding, then they are just an extra mouth to feed, and they are noisy. two roosters willl be problems. possible fighting, and if nothing else there is a pecking order, the dominiant one will generally make life miserable for the lower one. esp. if penned up. large breed roosters do have a tendency to become aggressive to people, esp. children. and if you dont keep the spurs cut, they can hurt you.
with all that said. if you keep one rooster, you will probably be ok. but i think someone should know worst case scenario.