But, as this thing evolves, and as there is no "diff" to see only "new" or modified parts, it starts to get a bit cumbersome to study
Seeing the sheer amount, and also, wrt to your "non serial" approach, i wonder, if it wouldn't be a good thing trying to "integrate" all of this in some sort of wiki or similiar, starting to get sort of a comprehensive documentation for X#.
I know exactly what you mean, but I can't at the moment think of a better and/or easy way to improve what I write.
For myself, I just use the search facility in the CHM.
Because I find out X# stuff from the work I am doing, in some sort of a crazy random fashion, I just record working code with simple explanations as I go along, in a semi organised section / subsection way.
If it were any harder (more difficult) to do than at present, then any fun would go out of the exercise for me. Then that would mean no work recorded at all.
I can't think of any easy way to just show a list, or highlight, of the material added - AND - I often 'add-to' stuff already there.
Overall its not an easy task, and without three screens it would be a nightmare!