Rules of War?

Well there have been at different times, terms agreed to by various countries at war. The most famous war rules are probably those laid out by the Geneva conventions. Here's the wiki if you'd like to know a bit about it.

http://en.wikipedia.org/wiki/Geneva_Conventions#The_conventions_and_their_agreements

The reason people don't use nukes isn't to be humanitarians, its more of the fear of mass retaliation and/or the losing all legitimacy and respect among other world powers. Nothin will get the whole world against you like a nuke.

For the gas, there have been several types of gas used since WWI that are generally viewed as being lets say "in poor taste" when used. The first one to be introduced into modern warfare was chlorine gas used by the germans on april 22, 1915 on the western front. They had actually used it once before in the previous january against the russians but it was too cold for it to work. Starting out, gas was incredibly deadly because no one was prepared for it but it could only be used when the setting was just right. The initial method was just opening up canisters filled with it and letting the wind blow it to the enemy trenches where it would settle in, so if the wind wasn't in your favor, good luck.

The chlorine gas heavily irritated the eyes and breathing of people that were exposed. Depending on the concentration and amount inhaled, it could just really mess up their lungs or it could cause them to fill with fluid and drown them to death. the germans got the chlorine as a byproduct from their dye factories.

In case you were wondering, toxic gas as a weapon is referred to as 'N-munitions'

If you're interesting in wartime technological advances or the inventions that led to modern warfare as we generally think about it, WWI is really the war to study. Personally, its one of my favorite areas of history.

Well it all depends on the battle. In the past some countries have stuck to the geneva conventions pretty closely while others have not. Not all wars have an 'anything goes' sense to them, some have been more willing to mutually agree not to use certain weapons, tactics, etc. Same goes for treatment of pows, which was originally the main concern of the geneva conventions.

Iraq got what Afghanistan deserved.

And it's in the best interests of most places to follow the Geneva convention. The only place that can really get away with not following it on a large scale is America. Not just because America is big or strong but also because they're psychotic hypocrites that will shit all over anyone that fucks with them (except Iran since the unbelievable boondoggle that is Iraq is continuing to ruin America's reputation and preventing them from nuking another middle eastern country).

Why have people voted No on rules of war being good? What kind of freak thinks that gassing your enemies, torturing prisoners, and using biological warfare is a good thing?

I'd say war is pretty natural. Animals fight in lots of different ways and animals as social as humans would naturally do it on a rather large and fairly organized scale.