Good luck, it sounds like you're on the right track, if there's anyone else in your home, make sure they understand how important it is to keep them entirely seperate. That is the one thing I really DON'T like about showing my dogs!!! I hate dealing with a girl in heat, I have a fairly small house, so even in seperate rooms the boys can smell the girl in heat, so my boys always get anxious and drop weight, and the girl will dig at the door of the room I put the boys in to keep them seperate because they want their boyfriend!
Is there a room where you can close a door to isolate your boy, or a top for your pen? Just because he's never climbed it before, don't assume he won't! I've heard of quite a few "oops" litters because someone assumed their normally well behaved boy wouldn't climb a pen or fence, and suddenly he did when the girl was in heat resulting in her getting pregnant.
As for spaying, I usually like to follow the advice of 3 - 3 1/2 months after a heat cycle before spaying them, but that's really a personal preference, the reason someone already mentioned - Weither or not a dog is bred, their body goes through the same cycle after heat.