Christ, Adam, and Salvation

In Romans 5, Paul explains the role of Christ in salvation in relation to Adam. How can Christ be a "type" of Adam, since Adam sinned and Christ did not? Does this chapter support the interpretation of universal salvation? Since all "died in Adam," will all "live in Christ"? Western Christian understanding of sin and its effects on the human race was strongly influenced by Augustine's interpretation of Romans 5:12. From Augustine's faulty interpretation, the concept of "original sin" was born and took root in the West. How are Catholic and Protestant concepts of sin and salvation different from the Orthodox understanding? What do these different ideas of sin reveal about our different conceptions of God and His relationship to humanity?