I don't think Veronica is affected (I do think Logan is deliberately so much of the time) -- my argument is that's the way she really is: she has a running commentary track, just like a character in a show. It's a step past being the hero of her own life; she's the star of her own life, which implies a constant imagined audience. Neither of them are stereotypical, but they think of themselves as characters; they are immersed in the generic conventions they use to define themselves. I therefore think they don't let the pretense slip so much as play the role of people with hidden depths. Their emotions are real, otherwise they wouldn't be so good at playing them.

The green-screen has to be deliberate. Without decent commentary tracks on the DVDs I can't get confirmation on this, but given the attention paid to lighting on the show and the current technological capabilities available, the only way to read it is as a choice, probably in part homage to older noir.