I think your essay is moving along nicely - gets stronger as you go along.
Right around the line "Moreover this guilt drives his future actions" as a reader I want to know what he did, prior to going to Afghanistan, to "atone" for his sins.
I don't remember him doing that much to redeem himself. Seems like his relationship with his father changes and perhaps he shows some courage in wooing his future wife. Overall though, I felt he didn't atone UNTIL he went back to Afghanistan, and then after saving the boy, it bothered me he'd tell him they wouldn't send him away and then he is caught discussing what to do with him.
You're right - he does eventually stand up for himself and works to make things "good". He could have chosen to walk away, but he didn't, though it could have meant his death.
As a child, some of his behavior was understandable - he was wealthy and the only child of a popular, strong and well respected man, but he didn't have the same drive as his father. Hassan was physically deformed, slow but his loyalty to Amir and his father raised his status, at least in their household.
Class had something to do with Amir's actions, as did his father's love for Hassan. I'm not sure Amir really got to start "living" until he saved the boy.
You might want to re-work the first part, offering a few examples of Amir redeeming himself. I'd say for the most part, you've done an excellent job. I don't feel I am right now - the brain isn't working right this morning. My apologies.