A FEW suggestions for (brunette) villainesses:
Khloe Kardashian (5'10", 34C-30-40...weight anywhere between 150-170!) she's brunette, and Kim (Ursula Wolfe) is already in the story, so Khloe's character could be Ursula's sister (!?) Having her dominate any of the blondes wouldn't be as unbelievable as little (5'3") Kim doing it!
Olga Kurylenko (5'9", 34-23-35 she's only about 120# but she's played "tough" in films)
Catherine Bell (5'10, 34D-24-35, about 125-130# and can 'kick ass' when it's called for)
Sofia Vergara (5'7", 38-28-39, 140#, and she's from Colombia)
A few (normal bosom size) blondes to consider for roles (with a nod to krispin) should be: Blake Lively, Charlize Theron, Candice Swanepoel, Yvonne Strahovski, Hayden Panettiere, or Taylor Swift(!)
Also, where are your "token minorities"? Beyoncé, Eva Mendes, Alana de la Garza, Nicki Minaj, Zoe Saldana, Gabrielle Union, Rihanna, Salma Hayek, Kelly Rowland, Penelope Cruz, Nicole Scherzinger, Alesha Dixon, Brenda Song, Michelle Rodriguez, or Eva Longoria (and that's just a few names off the top of my head!) You could throw in an Asian model/singer/actress (like MaggieQ, for example) as a "side-kick" to Jeri Ryan's character (give her a bowler hat ala "Odd Job" - just don't let her throw it at anyone!)