RE: Nitro fuel storage.
I store mine out in the garage. It can get humid, but it's usually dark.
There's no reason to store something as combustible as model fuel in your house. I wouldn't ever store a can of gasoline in the house..same goes for model fuel.
As far as moisture, obviously the less "head room" in the jug the better off you will be. But I don't think much moisture is absorbed through the container. I also believe the cap doesn't let much pass either. The bottle bloats in the heat, and shrinks in the cool.
Besides, I've had 1/3 full jugs sit all year and still work fine.