Lee:
I am vigorously hoping that someone is going to drop in and enlighten us and in a few sentences answers all our questions.
Failing that, however, I think you are going to find probably the best material answering your question in that DeLacey commentary, for example. All of this is very technical and as usual we are relying on commentators, some of whom are more sympathetic to Epicurus than others. I can't vouch for DeLacey but I remember thinking when I finished reading this work several years ago that DeLacey's interpretations seemed sound to me. This following clip is part of the material I linked in the last post above: