I don’t think that same feedback for multiple parts would work very well. There are many stories that have many parts, I think it would be difficult to navigate.( Then again maybe it’s nice for the authors to have all their feedback in the same place for that particular story.)

Not knowing if you have read the story or not (with feedback and story as the same thread that jumps up and down) wouldn’t be a problem I think, since read topics change colour.

Another idea I have (that I hope isn’t unbridled criticism) would be to have some kind of autolink feature so that a feedback thread is automatically attached to the each story, and you just can click between them.
But that might not be technically possible. and would require extra work on somebody’s part.

I do know you, and I know you wouldn't lie... at least to me...most of the time...