How do I properly jack up one side of my house?
It looks like the most cost-effective way to level the floor is to do it with this self-leveling compound system, pumped in by a professional.

http://www.youtube.com/watch?v=u2mVPjnVzVg

I mean, there appears to be nothing wrong with the walls, the house isn't moving, and it's only the back of the house and the upper floors that have the issue. 

As for the upper floors, they are easier -- I can rip out the carpet and flooring, add shims to the joists and do other measures to avoid the squeaks, put the flooring back, and the upper floor should be good for go.