how do they react when wet and is there anything you can put on them to make them water proof/resistant?
They shoot the same when wet out to 50 yards on my setups. I also use a biscuit rest on my hunting bow, so I'm sure they shed a LOT of water before they ever leave the bow. I've heard of powder you can put on them, but I really don't see the need to be honest. Just my personal experience.
I shoot feathers with a biscuit too and have had no problems when wet,also they dont distort like plastic.
now an even better ? do they freeze when cold& wet and if so how does it affect the arrow and if they do how can you combat that?
I'll be honest here. If it is so cold and wet that my feathers are freezing that means other things are freezing, including me, which means I'm not out hunting. I made a promise to myself a long time ago that I will never be freezing wet by choice. You can make up all of the scenarios you like but there is no scenario where feather fletching will not perform as well, or better, than vanes.
I don't shoot fixed heads. They will shoot Rage's to the same POI though when wet. Maybe it's the biscuit rest?
I have shot soaking wet feathers at 40 yards with fixed blade heads and noticed no difference in impact.I have tried the same thing with Razrs and I was lucky to hit the target. There are powders that work well and hairspray works pretty well.