Thanks for assuming that I'm serious because I am. I'm playing this for a concerto competition for our school. I probably should find proper instruction, but I can't afford it at the moment. I did save enough money to have one lesson with someone I found at the Music Institute of Chicago, but the level of help I can get will be very limited unless I find someone who has already played this (I'm not sure how I'd do this, but it's probably too late -- the competition is at the end of this month).
I'm going to try all your advice -- the fingertip problem is no longer really an issue. It turns out that I just haven't given my fingertips time to heal. I thought the calluses I developed would help, but it turns out that it takes time for the calluses to soften. Now it no longer hurts.
The fatigue is still an issue, but I'll try your advice with the wrists with slow practice. The problem with not locking my wrists is that there is some compromise with accuracy. I find that if my fingers leave the keys, they tend to lose their position (which remains static throughout the passage).
Thanks everybody.