Does it fit your needs?
It can be anywhere in the notebook with your tests:
"Run 3rd subchapter's group"
Cells[CellStyle -> "Subchapter"][]
; SelectionEvaluate @ EvaluationNotebook
About the issue of capturing inputs from the mouse scroll wheel: I recently found a way to do this after a suggestion by John Fultz. It's a pretty dumb hack, but it works and it seems to be the only way to do it.
The main idea is that there is one avenue for capturing something directly affected by the mouse wheel: the scroll bar in a Pane can be made ...