on #3. I am in that other group that had fallen off. I could not keep up, unfortunately. Although I check the lectures once in a while. And I think material is great. I am very very happy are doing this.
It gives such strong foundational background to understanding measurement models, contract management, programming language & database transformation models, etc.
For me, I got stuck somewhere on between lectures 6 and and 11 (in May), and could not become fluent in calculating left and right adjoins for all the puzzles you and other students posted. So everything was a struggle. Also I felt, I had to parse out every time, carefully -- differences in notations reflecting inverses/images etc. And some other things folks were mentioning (eg lattices/etc). Although, in the process, I think, I understood how to check my own solutions (which is a prerequisite for a good self-study). And yours and others feedback comments on what I had posted --was invaluable in that.
I felt, to keep up with the pace, and filling in my own gaps, in the process -- I needed to be putting continuously 3-5 hours a day.
Ultimately the efforts for my other projects -- was also too much, cognitively, and I felt they were higher priority for me at this time.
So I had to deprioritize the course.
My next thought was to print out various cheat-sheets/pictorial overviews -- from your course, and plaster it all over my office space -- so that when my eyes wonder of my work screen -- I can see the category theory :-).