Hey, thanks for your interest! I'll go through your questions in order:
1. As this is a kinetic novel (meaning the story does not branch), there's no tracking of saves between chapters. Each chapter after chapter 1 starts with an optional recap of everything that happened in previous chapters.
2. The Steam version is all 5 chapters at once, and we do intend to bring that version to Itch in the future! Right now we're keeping the individual chapters up so that someone who might have bought, say, chapters 1 through 3 can get 4 & 5 without needing to purchase the full-price collection.
3. We're very fond of the characters in this one too, and haven't ruled out revisiting them in future small one-off instances. We're also intending to feature a certain character from this story as the main character in our next story, which will have a much different genre and tone (not saying who yet!)
4. Really glad you enjoyed the AA/SB demo! We think about it often and do want to return to that world someday, but not until we're confident that we can do it justice.