1. I started in mid-August. No bugs! Never saw a mosquito.
2. I stopped carrying water because sources were so plentiful right along the trail. I would just stop and drink a liter. I kept my cooking pot handy so scooping water out of a small source was easy. Sometimes platy bottles are hard to get under water in shallow areas.
3 Looks like you have a good layering system to keep warm around camp…anorak and wind pants, wool hat.
4 Trekking poles are great. Remember you will be out for many days and miles. They poles will help keep strain off the knees. I did break one through a bit of carelessness, but was glad to hike with the one that survived. Luckily I only needed one to hold up my shelter (Six Moon Designs Oasis)
5 You can use the two poles to hold up your Poncho Tarp. Have a center line (parachute cord) run outside the tarp along its ridge line. Have a way to tie it to the hood. Your tarp will be in an A-frame shape. I was glad to have a shelter for warmth and one night of rain, but it was great just to sleep out under the stars. (You will not believe the number of stars) BTW if that poncho is your only raingear, have a rope or some belt system to tie off around your waist. Also be aware if you do use poles your arms will probably get wet under the poncho which has no sleeves. (I have the Golite poncho, but did not use it on the JMT) The one afternoon I encountered rain, there was also hail and I was glad to have waterproof shells to go over my hands and liner gloves.)
6 Clothing dries very quickly in the mid-day sun, so I even did a laundry which dried while I took a swim. Lakes are not as cold as the ocean in Maine!
7 That guide book looks great, but I just used the Harrison Map kit. I had zeroxed info from the Wenk/Morey Guide that has mileage and cross section chart so I could judge the ups and downs of the hikes.
8 I did not take the ferry at the Vermilion Valley Resort, but I left the jMT and hiked to it along the north side of the lake. There is a nice meadow to camp in in the valley near a good stream. I did pick up a food drop there and used the satellite phone to call home. There was no cell phone reception after Red Meadows and Mammoth until Whitney. If you do hike out from there, hike up the Bear Creek Trail rather than the ridge trail. The trailhead is about 3 miles down the road, so try to hitch to there, but the hike up that trail is fantastic. It is not steep and follows a beautiful trout stream. There is level camping areas just below the jct with the JMT. At Mammoth, I took a side trip up into the base of the Pinnacles for one night. Great hike, camped lakeside.
5 I was glad to have the expedition size Bearikade canister from Wild Ideas. It fit 8 days worth of food I needed after the Muir Ranch.
I went into the small store there to buy batteries for my camera. The clerk told me to look in the grab bag bucket where hikers leave extra gear. Batteries were there. I never used them, but I did not want not to have my camera. You will see why! It is easy to mail the Bearikade back in Lone Pine. It goes as is, no other box is needed.
6 Since there is no cell phone reception, consider the SPOT emergency system of a similar rescue beacon for peace of mind for your family at home as well. The SPOT lets you send out a daily message to e-mail addresses that will also pinpoint your location on a google map.
7 As you might tell, I enjoy writing abut my adventures on the trail. What an amazingly beautiful part of the world.
I have been back to Yosemite again and hope to head there this summer. You will see why!!
PS Have you done lots of miles wearing the "Five Toes". I heard they take some getting used to and would hate to have you have foot issues that might end your hike. I used low cuts which work great, but wore dirty girl gaiters to help with the dried out dusty portions of the trail due to horses.
A piece of gear I liked was my Dr. Shade which fits with velcro around any baseball-type hat to keep the hot sun off the neck. Take it off any time. Weighs almost nothing and packs smaller than a hackysack!