Man, I relate to all of this SO much. I think it's the nature of any kind of serial fiction to want to do that kind of updating--and the nice thing about the way we publish fanfiction is you can do it, if you want to. I made some edits on the first fic in my trilogy before publishing the third one, and now that I'm working on another longfic that's kind of the conclusion to a series, it's interesting to look back at the way my ideas progressed over time. Sometimes I want to update things; sometimes I just want to leave that visible train of thought as it is. But it's always interesting to see how your own ideas have evolved.

Good luck!!