1) Uniforms issued at NAPS have changed over the years. Within the past decade, there have been at least two years that NAPSters wore khakis. Most years they have worn NWUs. This year is the first year NAPSters were issued johnny cashes (the summer/winter working blues that you see so commonly worn at USNA). A couple weeks ago, several ladies from USNA came down to inspect each of our uniforms. Most NAPSters are now exempt from being required to purchase several uniforms at the academy if they were already issued them and they are still in good condition. Considering that roughly $6,000.00 in uniforms are issued at USNA, every little bit knocked off of that helps.
2) Beyond sports, there really aren't any official extracurricular activities. Many NAPSters play instruments during their free time, and also for the weekly Bible studies held for NAPS at the chapel. There's no way you'll be able to get hours in flying while at NAPS, except for while you're on leave.
3) I was a Mitchell cadet in CAP as well. I was told at MEPS that I would go in as an E-2 (Mitchell award will only get you E-3 in the Air Force). They filled out the paperwork for me entering as an E-2, but somewhere that got changed back to E-1. My understanding is you won't, as a direct entry, be able to enter as anything other than E-1. If you receive scholarships though, you can arrange once at NAPS to have those dedicated to cover your mandatory expenses (uniform costs, battalion activities fund, etc.). Info on that is provided during Indoc over the summer.