My questions are mainly about where I'm going to put it and pruning it. The backyard is tiny, our neighbors are right next to and behind us, and the yard is north facing (yuck). So the best option I've got is to put it in a northern corner so it'll get the most sun and not block out the rest of my tiny plot of land.

So my concerns are...

1) If I pruned so that the tree does not invade the neighbor's property, it will definitely be off-balance. Will that be a problem? Or will the roots balance it out (into the neighbors' yards, probably, but at least it won't be in their way.)

2) Pruning for height. How low can I prune a peach tree without impeding its yield and health? (Not to mention I'm pretty darned short.)

Thanks in advance, folks!

Being off balance won't hurt your tree. At worst you might need to put a support under parts that are weighted down by fruit. But if you are thinning the fruit properly and pruning to keep the tree short it will support the fruit without leaning.

6-8 ft is doable with regular summer pruning. That size won't hurt the trees health at all.