"Even if eating the apple was a sin, it was Adam's sin and he is responsible -- not the rest of us. The way moral responsibility works is, people are responsible for their own wrongdoings, not the wrongdoings of others. So the rest of us don't need to be redeemed for Adam's "original" sin."

Each of us has our own sin we need to pay for, not Adam's.

"Even if we are somehow responsible for Adam's sin, we are the ones who must then redeem ourselves. You can't redeem someone else by dying for his sins. The guilty parties must redeem themselves by paying restitution to their victims, promising not to do it again, etc."

A question I'm still seeking an answer to.. how is it just that a perfect person pay for my sin? but I think justice is an eternal issue that won't get dealt with fully on Earth. It sounds like a cop out, but I believe everyone is judged for the wrong they do in heaven.

"And even if we could be redeemed by having Jesus take our punishment, Jesus didn't take our punishment. Our punishment was supposed to be hell, but Jesus ascended into heaven."

Hell is seperation from God. The other place, that has no place in heaven. I believe that Jesus was seperated from God and it's why he cried during the crucifixion "Abba, Father, Why have you forsaken me?" (forgotten me).
Yes, very true it wasn't for eternity, but God is without blemish. Very different to our position, can't really be compared.