As for the name, I've always been confused by the author's choice of the Twilight theme. It still doesn't make much sense to me. I'm sure she had her reasons and has explained it before, but to me it just doesn't fit properly, and if she really has had to explain the Twilight theme, maybe it really was just a poorly chosen title and theme.
There's a comercial on it now which says things like "Between Light and Dark", "Between Good and Evil", "Between Life and Death" so maybe that's it.

MJN: How many people have ostracized you for using the word "Twilight?" While it's true that I once considered the possibility that I am in reality surrounded by turd-flinging morons, I have to doubt that so many people would have been alienated from your creations simply because you used the word Twilight.
I haven't used "Twilight" in anything yet, but I have seen it happen to other people ("I closed this as soon as I saw"Twilight"!" "Do have to see the word "Twilight" everwhere I go?"). If the word seemed relevant I would be tempt to use it though.