There are some things that must be ntoed, and I failed to mention that, when you talk about that the incarnation is not a contingent event. It is that the fall is not strictly speaking a fall in the past where mankind lost some paradisical state. Rather it is a part of the history of creation, it starts off that way, but the goal of all of creation is to be assumed into Christ. This is a more Eastern view, although quite typical in many of the church fathers. For those views, the incarnation is not a rescue attempt of some failed creation, but the process where creation is fulfilled. The goal of all creation is to become new creation. That answers your second question as well. Adams sin touches all, in that we all are that way before we are perfected in Christ. And I lean towards universalism, I believe that ultimately every knee shall bow to Christ. The incarnation is the goal of creation, the absolute central event of it all, where the true purpose of creation is revealed.