Dana,
Your questions and concerns are more than valid. As to why nitrox, let me say it like this, I do between 75 aand 150 dives a year, some times 5 or 6 dives a day. I find that nitrox 32 is great for making me feel good after that many dives in one day. (no Mdeical proof) All I know is that I felt the same way as you and so did Roxanne, until we started diving it. The feeling of well being is by far just a personal thing, bet when we dive in North Carolina they call it geezer gas. Hope you have enough information to help you make an informed decision.
Clay