First, did I make a mistake in buying a six string as opposed to a 4 or 5 string?

Probably. At least in not considering this: What type/style of music do you want to play?

Is it possible to learn to play without being able to read music? I have the desire and the commitment but not sure which direction to go. Do I attempt to teach myself or should I take lessons.

Self taught (well I did buy a book) tenor banjo/mandolin who can understand basic music theory but can't sight read here...

Any help you can find, ie. if you can learn to read, can find a good teacher, etc. I think has got to help.

That said, you may get by without and you have the most important qualities, I think in desire and commitment.