Mimi, is it a really dry read?

Lots of really big questions here....
Tom4Uhere, I'd say at least for question 1 on the definition of a Joule: there are a number of ways to quantify it, here are just a couple.

One way is to think of a joule as the amount of energy that you obtain if you were to push an object with 1 Newton of Force by a distance of 1 meter. If you guys prefer imperial units, it's like applying a force of 4.45 lbs for a distance of 3.28 feet. When working with machinery or cars, it's easier to visualize the energy as if you were pushing or pulling something over some length.

A Joule is also a convenient unit to use when figuring out power. If you run a pump or motor at 1 watt for 1 second, you've consumed 1 joule of energy.

Source of info is wiki also: https://en.wikipedia.org/wiki/Joule

From a philosophical standpoint, how much energy is actually in one Joule is hard to determine. The way I see it is, we have trouble understanding what energy really is, so we reconcile that by using concepts like a Joule to be able to measure and calculate with.

Also, for your question 2 about absolute zero temp, have a look at this article. I came across it a while ago, and I think it might interest you:
http://www.nature.com/news/quantum-gas-goes-below-absolute-zero-1.12146

I remember in school people would ask: 'if we ever hit absolute zero, does that mean everything just collapses in on itself?' I still don't quite understand how it works. But it seems researchers have found out that we can go below absolute zero, and the material still holds together, and behaves differently. Really cool stuff.