Help with Questions to Moby-Dick: Is Ahab justified in seeking personal revenge

Is Ahab justified in seeking personal revenge for the deep harm done to him by Moby Dick? Is Melville interested in sympathetically portraying his monomania and obsession? Or does Melville depict him as an arch-villain driven to madness (“madness maddened”)? What is the effect on the crew of his dominating, authoritarian personality and his making Moby Dick’s the main “evil” since Adam in order to justify himself?  What is the significance of his smashing the quadrant, defying the sun, first concealing and then using Fedallah, and his control of the crew through a diabolical sacrament? In drawing a portrait of Ahab, was Melville depicting an American character type? Does he have contemporary relevance for Melville – or for us?