The measure of a man is a man. Justice, morality, ethics, fairness, goodness all based on the preservation of life. You can do other things, but you'd be Good by coincidence.

4 ways: Agnosticism, Relativism, Amorality, Morality. 

1) I don't know. 2) Everybody is different. 3) Do whatever you can. 4) Do what you should.