1) You can weigh human life, but that weighing will be totally biased. If heard of a story of a mother who had some children. One of them was a daughter that was raped. She demanded that rapist should be put to death.
Some time later, her son, raped a girl. You would suspect that she demanded the same? No! It was her lovable son, he was provoked by that sl*t and he is innocent.
So you see, the weighing is biased, like I said before. Because of this weighing we had fascist and communist regimes. But the problem also dwells between normal people, who put etiquettes to others. This is also weighing. We weigh based on university a person has graduated from, we weigh a person by his education/parents/town/language/carnation. You name it. You have it.
Weighing is bad. But we cannot escape it, everybody weighs other people, sometime completely unconsciously.
2) I was once for death penalty. But over time it came to me, that this is the easiest solution but not the best one. It's really easy to kill an individual instead of trying to "fix" him/her. You can easily punish someone else, because you have morality. But where did morality came from? From you? No, morality came from your parents, brothers and sisters, friends, society, people you meet on the bus. If you are lucky, you will have some morality (although still you can have some mental disease, but that's the other case). But if you are born into bad neighborhood, with prostitutes, drunken, addicts, people killing each other, what will be your morality? I think, that since you were "better" born, you are responsible, for at least trying to help such people.
But on the other hand, if I will be attacked by such person, I will retaliate. Life is brutal, life is unjust.