it's objective morality
most people would look at Hitler and say Evil, he and those around him would say Good, this can be applied to anyone you look at, anyone inherantly Good, if looked at in a certain way could be seen as Evil, and Evil as Good.
Good cannot exist without Evil and vise-versa, it's a comparitive scale, if there was nothing that we define as Evil in the world, no plague, death, famine etc. and there never was, then there would be no Good either, it works the other way round as well, without anything to compare something against, you have nothing to compare.
Good and Evil are moralistic, if your beliefs and morals tell you that something is wrong, you will see it as Evil, if they tell you that something is right or correct, then you will see it as Good
your last question, that is a something that is in our genetics, animals do not hunt for sport, like Mur said, we were animals once, apes (based on theory of evolution anyway), and in our genes was to ensure the survival of the species, we've kept that trait, but on a larger scale, we hear about someone getting hurt or killed it is against our species and thus hurts it, as we want the species to continue we dont like it happening so moralisticly people would find it wrong.
BUT, there are variations on this rule, if what we're doing ensures the survival of a larger, or more important part of our species then we will see the situation as Good to do these things, important would be from the individual's perspective.
this is what comes to mind currently anyway