+1 for Bob and Mary's comments.
Yes, you REALLY need rain pants or at least water-repellent wind pants. Expect a lot of afternoon-early evening showers and at least half a dozen snow or hail storms. You will be walking in cold, wet conditions a good portion of the time.
If you carry wind/rain pants, you may consider leaving out the thermal bottoms. I carried both and never needed both simultaneously. If I were to do it over again, I would opt only for the wind pants. On colder nights, I just slept in my wind pants.
Wind shirt. +1 on Bob's recommendation, however, since you have a rain shell, I would recommend getting a long sleeve shirt as your primary hiking shirt that has good wind and rain protection. I use a Columbis PFG L/S shirt and it blocks wind, has good water repellency and has 50 SPF sun protection. Also, very good back ventilation. Retail price is about $45.00, but you could probablaly find it on sale. Much cheaper than similar quality shirts like Rail Riders. I think the snap front is better than the button front style. The material is lighter and breathes better.
Hydration. There will be a few long dry sections where you will need to carry at least 3 to 4 liters of water a piece. So you will need something else for water storage. You may consider some disposable 32 oz. gatorade/powerade type bottles to supplement your permanent storage.