Collecting a series or serializing a collection?

I've been writing Subtraction, rewriting the middle while editing the beginning and dreaming of the end. It's all coming together, at last. There are pieces of the story that I really love - places where Andrew, seeing ties to the past taken away, sets his sights on something more; places where the mystical cat sets her sights very firmly on Andrew; places where... And yes, there are pieces I still hate, but I'm working on them. I remind myself Divide by Zero and Infinite Sum both needed lots...