To the question about my view of Jesus as the second adam, I don't think my beliefs about whether or not to accept Genesis as historically accurate really impact my opinion of this. I think Jesus allowed humanity a fresh start and clearly preached an apocalyptic message (to me His central message) of a future kingdom where humans again live in harmony and obedience to God just as in the Eden story, hence the idea of a 2nd adam.
there are several things I would respectfully disagree with you in what you wrote, but I want to focus on just this part at this time, lest our posts become too long.
so, I think your answer is no, you don't really believe that sin entered the world through one man.
would you disagree with Paul's message in 1 cor 15 that "Christ died for our sins according to the Scriptures"?