I used to think that Daken's mohawk might have been part of his mutation (because who gives themselves a mohawk at age 9, and Logan seems to have weird hair issues too) but at times the rest of his hair starts to grow in a little, so I'm assuming he shaves it that way.

You're right about him looking really old. He's fourteen and he has a furrowed brow. Stressful life, I guess. Nothing like murdering your parents and living with Romulus to make your balls drop.