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).