First tours are great, you will (hopefully) love it. As for your questions, I'll take a stab.

1. I have never heard a touring cyclist complain about have too low of gears. Go low, I think you do in-fact need lower gears, swap out your from chainrings for 22/32/44 or any combo that starts with 22.

2. If this is a first tour, and you are asking this question, I would recommend using Adventure cycling routes as a base for your overall route. Make your own route south to the ACA Northern tier and go west, connect to the Great Rivers route south, to the TransAm west, finally take the Western express option until you have gone far enough west for you destination in NM.

4. I suggest regular cycling shorts, you can always put baggy shorts over them.

5. Sounds good, 50 is a little conservative, but start out that way and see how it goes.

6. Your in good condition, you will do fine, just start out slow.

7. Figure about 300-350 miles a week for the duration.

8. I'm not sure about this one, maybe someone else will chime in.

OK that's all I know, are you writing a journal on Crazy Guy or some place like that?