Thanks, Rod, for the useful summary.
So Rod, for whom I have enormous respect, still agrees with Porter on this. If Jesse wants, we can discuss why some people agree with Porter and others with Fanning, but that's a bit much for the Beginner's Forum.
Jesse - you're working through Mounce. I think Mounce is particularly good on the morphology of verbs - his Summary of Basics of Biblical Greek
is worth having on your hard disk or printing out and putting in your Bible, it has great tables that explain the form of verbs clearly.
I also think that he's a little fuzzy on what these verb forms mean, and some of that has to do with the time he wrote the book. I suspect that the excerpts of Rijksbaron, together with Mounce, might be helpful for learning the traditional view of how the Greek verb functions (Rod calls this the Fanning view). It's been helpful for me. So that's my personal recommendation.
Unless your teacher is in the Porter camp. If so, I don't know anything better than Rod Decker's summary, which you already have.
ἐξίσταντο δὲ πάντες καὶ διηποροῦντο, ἄλλος πρὸς ἄλλον λέγοντες, τί θέλει τοῦτο εἶναι;