Good stuff, EJ.
I wouldn't worry too much about memorizing statistics or getting into things as though they were a university lecture. Discussion on the radio is often more effective if you just start with the broad strokes and stand prepared to break it down into tidy, successively more detailed pieces of information.
So the basic idea of webfiction is that it's posted regularly in (complete) pieces online, often with lots of cliffhangers.
Amazon thinks it's interesting enough that they're sponsoring some, but that's only a small piece of what's going on.
This isn't a new thing. Serials date all the way back to the days of Mark Twain, who would release his books in pieces through the newspapers before binding them together in a complete package. (This is one area you'll want to research).
Serials tell a different sort of story than you'd get with a novel. You learn to anticipate the climax, twist or conclusion with novels because you know there's only so many pages left, sort of like you do with movies. Serials are more like TV series, they're more involved, they sprawl, and aside from the conclusion, you don't know what to expect and when.
A novel is more like a big meal, but serials are like a snack. They're good if you tend to finish books too fast or if you want something to occupy yourself on a coffee break.
With lots of serials, the author can hear what the audience likes and doesn't like and shape the story in little ways.
(I'd suggest sticking to one way of referring to them, because we'll see better results if you fix it in the audience's mind that these are serials, rather than confusing them with Serial/webserial/webfiction/efiction, etc).