To answer your questions...
1. Smellables...Yeah, you are over thinking this. I rarely throw the lip balm and sunscreen in the canister, mostly because I forget to. I have never had a canister attacked by anything other than a chippie. I have had elfin bears go after GORP I left in a pack pocket.
2. Water to the summit and back...3 to 4 L depending on how much you drink. I'd need as much as 5 on one trip from Trail Camp...thank God for snow.
3. Warmies...If you get on the wrong side of a cold front, you will freeze your rear end off. I have been on the summit in August when the temperature was less than 10* F...according to my pack thermometer plus the wind was at a solid 30 MPH. My normal Sierra core set up is a 15* F bag, summer weight down jacket and Driclime wind shirt...sometimes this is not enough.
4. Distance to Cover...Yeah, you are well above the treeline at the Tarns. The treeline ends at about Timberline Lake.
5. Diamox...Taking 2 X 500 mg. your extremities will tingle the whole time you are out and it will take 3 or 4 days to get it out of your system. My guess is you will be ok without it because of your history and that you be will going to elevation gradually. I only take it the few days out and at a much lower dosage.
6. Other advice...Be on the summit at dawn. You will not be disappointed. The hardest part of this is staying on the trail from the Tarns to the west switchback...just keep you eye on the trail and you will be ok.
