Cheers for the praise, guys, much appreciated. To answer some questions...
I use Flash to do almost everything in nowadays. Damn good for drawing, animation, and multimedia.
The minimalist style is what it's all about, although I tend to get a bit carried away if I'm not watching. Clone Wars is a good start, tho I expect to do it a little more elaborately in some areas (ie: not using vast amounts of repeating extras, like clones and droids, and a little more realistic looking people), and less so in others (I have no 3D skills, so the spinny, twisty, rolly ship maneuvers are too much work). I think some of Clone Wars is done in Flash, actually.
The mature element in the script involved a baddie plucking out the eye of one of his lieutenants - it was in silhouette but there was copious ichor.
Voice talent ain't such a problem. I'm ok myself, and I know several actors who owe me favours.
 
I think I'm aiming for something between Aeon Flux, Cowboy Beebop, and Futurama.
I would animate the script but I have to write it first. I lost the one I'd done before when my drive died; I want to rethink it anyhow.
That's why I want your advice: crew composition.
My current thoughts are...
Captain, oldish, curmudgeon; based on Mark E Smith
Pilot, dashing south asian navy deserter called Cyril.
Siadwell, odd jobs, hardly talks, based slightly on Hunter S Thompson.
Panthera, Zho first mate; she has secrets.
Bodi, diminutive drive tech/ cook: "Ooh, that's a nice bit of fish."
Loomis, Hiver 'owner aboard', finds illicit jobs and causes trouble.
Mr Krum, Loomis' Ithklur bodyguard, serene, ascetic, keeps bonsai.
and finally,
Kaia, Captain's daughter, arrives in pilot; 18, computer expert, has secrets.