That's an interesting way to think about it. Inflation only becomes permanent through default. If everyone defaults, there's a ton of inflation (as we have seen), but if everyone pays off their loans, the money disappears, and we get deflation. You are right on the first point.
As to your second question, when you pay off the loan, the money simply vanishes, much like it just "appeared" when the loan was issued (based on a fraction of the amount loaned being in their vaults--supposedly). When you pay back the loan, the principle disappears, but they keep the interest, which they can either keep in the vaults to lend more money, or take as profit and spend.
It's a man eat man world, not by nature, but by the machinations of the bankers. They have set us against one another while sitting back and collecting interest on the whole monetary system.