For those guys doing motifs - it's been a while, but I distinctly remember that there were a hell of a lot of metaphors used in the book. Additionally, there is a lot of reference to art (paintings, film) in the book... think about the 'constructed' nature of the book + lyrical prose, and you've got what's technically a freakin' piece of art. Think about the fact that art is again, a metaphor, and voila...!
Sorry I can't help with the light and dark, I can't remember that far
Is it a literal referrance to light and dark? (ie all the meaningful stuff happens at night, only highlighted by the daytime/dramatic events?)