Re: how much honey to leave?
If this is your first winter, my advice is to leave at least a box more than you think/are advised you will need. People tend to work from averages, even people local to you, and you don't know how good/bad this winter will be or the overwintering capabilities of your bees. Which would you rather have, a little harvested honey this fall, or a living colony in the spring? Besides, once the honey is in the system, so to speak (meaning the bees have it for stores), it has basically filled the storage 'pipeline'. If they need it in the fall, winter or spring, it is there to use. If they don't need it, then they will just start filling supers that much sooner next spring. It's not like they are going to go off and sell it at a roadside stand.
Once you have some personal experience in your own bee yard under your belt, you can back off or add, as you see fit.
Anyway, that's pretty much my philosophy - bees first, me second.
If you want to gather honey, don't kick over the beehive. - Dale Carnegie