Huh. d20fool, I'm suprised that you, a teacher yourself, would say this. In my experience there is one thing that impacts a classroom more than a quality teacher - quality parenting. Respect and desire for education begins at home. And the teacher generally can't do diddly if the kids don't have it.
Amen! However, money doesn't grow on trees. You know that respect and desire for education that begins at home? Well, it's the parents who pay the taxes that go into teacher salaries.
Well, that depends upon what you call "qualified". There may be a great many people who have the technical knowledge of their fields to teach. But teaching itself is a skill set that you don't usually get without doing it.
Plus, it depends upon where you live. In Massachusetts, for example, within the next two years, a full 40% of the public school teachers will become elegible for retirement with full benefits. And in MA, while the salaries aren't up to corporate levels, the retirement package is pretty darned sweet for old-timers. There's very little incentive for them to stay on, and MA may well have a serious shortage of people who are qualified to teach.
I am not going to speak on the subject of NCLB. I think of it as far too political to touch here.