Everyone here has great advice about stallions. I especially agree with not keeping a stallion up. I would NEVER keep my stallion up unless some emergency called for it. He just acts so much more "normal" when out. I leave him out in the pasture with the mares to keep him happy, unless I'm working with him.
Last year while I was out in CO, the geldings somehow broke into the mare pasture and my stud was there too. My father called me and told me the deal but said that Amigo wasn't bothering the geldings at all. He ended up staying with the mares and geldings until halfway through winter. He is EXELLENT around both and doesn't mind the geldings buddy-ing up with the mares as long as he get's to "Sleep" with them lol (can I say that?)

A child could hand-breed him to a mare. He will walk by your side as you approach a mare and walk as slowly as you want to walk, keep his head to your waist-height if you'd like, and keep his eye on you in case you have another request for him, all the way up to the mare. When I let him go, he walks gentlemanly up to her and get's his business done.
I also ride him with mares and other stallions and NEVER get even a whinny out of him. He is awesome. But I know that is not the most common type of stallion. I would definitely say though to anyone getting a stallion for the first time, to let them be able to run in a pasture instead of being cooped up in a stud barn!