Glad to hear you've nabbed a much coveted spot on the JMT. While not having done it myself, here are a few things I'd consider for your list:
While a base weight under 20lbs is good by traditional standards - I've noticed that many in at this site strive for around 12lbs or less for an all out base weight (gear carried, backpack) if possible. I am not familiar with hammock camping - being a die-hard ground dweller myself, but it seems to me that a large amount of weight could be saved by moving to a tarp / neoair setup (I used a Neoair large + MLD Cuben SoloMid + GG Polycryo groundsheet on the A.T that weighed = 30 oz. including stakes).
For a well illustrated and informative read, consider reading up on a few articles on the site about how to drop some weight from your "Big 3" (sleeping bag, backpack, tent) and get dialed in on your incidentals (med/repair kit, headlamp, cook set, firestarting, camera/phone/maps, bug deterrents, etc. I really enjoyed reading Mike Clellands book on Ultralight Backpacking tips.
Poles: I never hike without my trekking poles. Save my knees, my face, and just pretty much all of me from my own tripping stupidity.
My Dri-Ducks $20 rain set lasted my about 1,600 miles on the A.T. last year with only 7 duct tape patches on the jacket ..and pants eventually got torn to shreds -- but well worth it for my style of hiking -- fast and light.
I'll let the much more experience JMT'ers take it from here. Cheers and happy trails !