1. Had one occasion many years ago where I resorted to getting water from a barrel cactus. (We had plenty of water in the Jeep, but that didn't help when we lost the Jeep. Thus the orienteering courses.) It didn't make me throw up, but it did taste really, really bad.

If I had to do it over again, I would have made a solar still and thrown chunks of cactus into it.

2. Never had to rely on this one, but I will bet that in most cases the north side of the tree is the "proper" condition since it gets the least direct sun. But you are right. In dense forests, I have seen places where moss is everywhere.

3. Another one I have no experience with. I generally don't drink cold drinks in the cold. I read somewhere that the body is pretty good at adjusting the temperature of just about any liquid to body temp by the time it reaches the stomach.

4. I have a good experiment for this one. Get naked in a blizzard as see what falls off first. I suppose all surface areas of the body lose heat equally, but the body begins shutting off blood to the "less essential" parts. Also, some parts are just harder to supply blood to (farther from the heart, fewer and smaller blood vessels etc). That's probably why most frostbite injuries occur to toes, fingers first, then noses, ears.