I may have to re-write that whole post with a new title. That may take a few days.
But I have revised #1 as follows:
“For example, the concept of anicca is understood gradually—from the Sotapanna Anugāmi stage to the Sotāpanna stage. Then how that anicca nature leads to suffering (dukkha) is fully grasped in stages — strengthening at the Sakadāgāmi and Anāgāmi stages — and is fully comprehended at the Arahant stage.”