RE: feathers in the rain
You're not likely to get a shot during a pouring rain, and even if you did the rain would wash away any blood trail and make it hard to find your deer. Not a good idea to take a shot in heavy rain, IMO.
So, slip a freezer bag over your feathers to keep them dry in the rain and wait it out.
If it's drizzling and misty, any good waterproofing agent will keep the feathers dry for an hour or so, at least. Keep one arrow handy and ready to shoot, but keep the rest of your arrows under plastic. Switch to a fresh one when your feathers start looking too wet. If you can keep that ready arrow under some kind of cover while you wait, you won't have to swap out very often.
I've used plain ol' Scotchguard for years. If it looks like rain, I'll spray my feathers the night before hunting and let them dry overnight.