It's hard to say - passages that haven't been on exams before of course.
But they could have anything to do with anything, really.
The VCAA just doesn't choose random passages, though, so in my opinion you're better off choosing a few 'significant' moments or those with themes you can see relatively easily - at least at this stage.
Do you mean how many of the three you have should you include? All three, I say. I usually tell students to focus more entirely on two, and then just refer to the third (the third being the least relevant to your thread, or your contention).
Oh god, books to read! It's been a while since I've had a chance to read a book that wasn't on the Literature and Performance list, and they were all great classics by Dickens and Austen.
My favourite author is too contemporary for the Lit exam though, which makes recommendations difficult. However I love Jane Eyre, but most everyone has read that (I think?). If you haven't, read Jane Eyre!
Classic literature is good - I want to read more EM Forster stuff when I have the chance, and perhaps a little more Dickens although I did find Great Expectations a little draining because of how long it was and how I had a week to read it.
If you want to read plays, read or view Ibsen plays, but that is kind of similar to Chekhov so it wouldn't be broadening your horizons toooo far.