Hey - I wouldn't worry about bears. And, when you say you are going to be drinking hot chocolate in your bivi sack, that is a huge no-no in bear country (I live near yellowstone).
Personally, in the catskills, I would eat in my shelter and hang my food (out of habit, and more for squirels) and I wouln't worry about bears at all.
I would NOT take a full size nalgene botlle. Take a wide mouth soda bottle (but don't pour boiling water in it, just a little under boiling is fine, it'll warp the shape and the lid wont fit anymore)
And - Don't take a cozy, just stuff it in an inside pocket. It'll warm YOU and stay insulated.
Maybe fine a wide mouth plastic bottle that easily fits in a pocket. Juice bottles come in a million different shapes and sizes.
Nix the stuff sack for the tarp! Just because it's fancy and new is no reason to use a stuff sack. Just cram it in your pack FIRST, add the pack liner on top, and let it fill the space UNDER the pack liner. It'll be fine.
No need for "a couple of liners" one is fine