Cuchulainn

In the Tain, Cuchulainn is depicted as basically the perfect warrior- he is brave, noble, dangerous and handsome and saves Ulster at the young age of seventeen. Achilles, Hector, and the Pandavas, the heroes of the Iliad and the Mahabharata were not without their own faults yet Cuchulainn seems to be faultless. Were there any flaws in Cuchulainn's character?

Achilles

The Iliad ends with Achilles returning Hector's body to his father, an act which essentially humanizes him as it cures him of his excessive pride or hubris. We know that Achilles will eventually be killed by Paris, who was a complete coward, and many consider this to be his ate, or ruin caused by hubris. But because Achilles was reformed of his former prideful self can it really be said that he suffered ate and was therefore ruined?

Pandavas vs. Kuaravas

I don't completely understand how the feud between the Pandavas and the Kuaravas began in the first place. Was it just the Kuaravas' intense jealousy that led them to act out towards the Pandavas and ultimately go to war with them?

And for that matter were the Kuaravas merely fulfilling their own darma by acting out against the Pandavas (trying to burn them in their home, cheating at dice and then banishing them, etc.) in order to maintain their empire? Or would this have been considered adarma because these were backed by selfish reasons?