I read the first book of Lackadaisy and while I dont remember a whole lot from it, I do remember liking it a lot. Either way, I'm wholly in support of this: Faust has a great understanding of cartoon aesthetic and stories with legitimate steaks. Let's also not forget she was a writer for Powerpuff Girls and an animator for Iron Giant! And a superb cast of talented voice artists. Your choices would definetly keep in in the cartoonie feel. Nothing against big names, but they can be distracting.
One comment tho: if you're gonna get Graeme Revell to do the music, have him do straightforward 20s music, none of that "old school meets new school" stuff I hear in so many adventure movies nowadays. I feel it'd make the atmosphere more dramatic. Then, at the credits song, go more modern with some electro-swing. My money's on The Real Tuesday Wield or Caro Emerald.
Seriously, this needs to happen. Lackadaisy is long overdue for being animated and at least put into full on shorts. I like the voice cast you chose and the directorial crew I could see turning this into a hell of a movie. (Especially given all the awesome cartoons that Mrs. Faust has worked on, Foster's being one of the best, I believe.)
Though, I do think you're music choice would go well...I think just a little Parov Stelar would be nice in this movie as well. I could always see Rocky and Freckle getting into some trouble to the tune of Booty Swing or the guys putting on a show of Groovecat at the Lackadaisy bar. That's just me, though. Not the full on movie track...but just one or two of Stelar's songs in there to keep the 20s mood.
(If you've not heard of Parav Stelar, I highly suggest looking his work up. Booty Swing, Chambermaid Swing, Catgroove, and Mojo Gang Radio are four of my favorites and four of his best known songs. He plays what they now call, electro-swing. Severely catchy stuff.)
I was thinking maybe...use your suggestion for the actual movie track and maybe Stelar's music for the opening and closing credits...like, maybe Booty Swing for the opening credits, introducing the cast of characters (the characters themselves, not the actors) and the ending credits would be accompanied by Catgroove, showcasing various stills from the movie or maybe an epilogue.
To be honest, I've been thinking this very thing for the longest time and have the opening credits (with Booty Swing in mind) about...70% or 80% mapped out already. If only I could animate or do well enough storyboard, I'd be set. If anything, I'd love to make a fan movie of Lackadaisy...I just lack the utter talent that Mrs. Butler has.