Walt1957:Thanks to all for your informative answers. An affirmative to #1 negated a need for an answer to #3, for my purposes at least. It was not a desire to avoid the expense, or time of a nitrox class. Unfortunately I have not been able to find one scheduled at any dive shop within an hour drive. And none of the articles I had found included the risks, which I suspected existed but were unstated, which was why I asked here.
Where are you geographically located?