trOmbley,
I'm not a big fan of the utilization of Diamox without some history, but that's me.
The REI Endeavors are soft shell pants, which I happen to own. The are water repellent and wind resistant, not waterproof and windproof. Most light softshell pants cut about ~70% of wind and are water repellent when new. I own 3 other pairs, which I use all winter.
I like a couple of pairs of gloves for this trip, especial if it cold and you are wearing your gloves most of the day. They get damp with sweat and lose their warmth when you stop.
You can cut a 1 1/2 lbs. with an Ursack. I own Bearikade but I will use the Ursack in place they are legal...and they are at Mt. Whitney.
Depending on temperature, you may want a closed cell foam mattress in addition to your Therm-a-Rest. I have spend a few night wish I had brought a second pad in the Sierra in the month of October.
Staking your tent should not be a problem. You should be prepared to guy it out. Trail Camp can get awfully windy at times and I have seen tents on this mountain where they were not left a few hours earlier by their owners.
