Well, first of all, d20 is a really poor system for modelling the books. Especially the magic system. The sorceror is a decent way to model evocation, and the wizard would model thaumaturgy. But only in the most rough terms. And, of course, a sorceror/wizard is a terribly inefficient build, which would hamstring Harry.
You see Billy as still in the ECL levels of Werewolf, with no actual class yet? I suppose I could see that.
I'd have to disagree with you on Murphy. Fighters don't get nearly enough skill points to be cops. Fighter/rogue would probably be best, from the core classes. I could even make an argument for monk, but I don't think it would stick.
No class for Marcone? Rogue is most likely, though with some unusual skill picks (focusing heavily on the social skills).