a word of advice: I was a career runner through high school and college. three seasons of track, etc before i picked up cycling. it was a wake-up call. just because you are young and fit does not mean that directly translates into cycling ability, especially if you have some climbing to do over the course of the tour.
my advice is, while the gear end is relatively important, your cycling fitness is much more important. working out things right now like what saddle works for you for 8 hours at a time, what you can eat while riding, and most importantly, getting some cycling miles in your legs; these are all key items.
let's face it, when you're on the road, you can almost always find someplace to stop and improvise your gear, but something new, etc. the one thing you cant buy is more fitness, mental and physical preparation.
i'm a noobie aspiring tourist myself, but i've done a lot of looong rides, and what makes the difference between a fun memorable ride and a sufferfest is preparation,
good luck!