I’m also one who’s gone from a 1 to a 4 over the last few years, and I don’t recall spending much time (if any) in 2 or 3.
As to the first question, I think creation is pretty foundational to my beliefs – I couldn’t really imagine being a Christian without believing in God as the all-powerful creator, which is why I wrestled so much with it, because contrary to what some well-known YEC personalities claim, it’s not a simple dichotomy of “believe in a young earth or throw out the entire Bible.”