For some reason, I'm having the hardest time finding a good video, but Mary Elizabeth McGlynn for Zandra. Voice of Motoko from Ghost in a Shell, Julia from Cowboy Bebop, did all the singing for the Silent Hill music and is just generally pretty awesome.
I picture Tex sounding like her playby, Keira Knightley (I'm too lazy to find a video), with the cut-glass English accent, simply because she's studied language a lot and I imagine she's learned pronunciation and speech the 'official' way (and it wouldn't be her first language). Which ironically means in terms of the universe, she sounds more like an Imperial than a Rebel.
However, I like to imagine it's an affect she puts on, since The Clone Wars is pretty clear that most Twi'leks speak with what we consider a French accent, and so when she gets really stressed or angry her natural accent comes through, at which point she speaks with more of a French accent.
I dunno about this movie,but my character is voiced by a Canadian Actress named Neve Campbell. I'm sure you've heard of her through the Scream saga. This is a clip from the movie,"Wild Things". I never watched it,but I remember hearing that Neve was the villian villain in this movie. A justified villian perhaps.