Ok so I finally have some information on the English dub VAs, courtesy of Wikipedia.
Clare:
Stephanie Young
Raki:
Todd Kaberkorn
Teresa:
Christine Auten
To be honest, I've never heard the VAs for Clare and Raki, so I hope they do a good job. Especially Clare's VA, given that she's the main character.
Christine Auten, however, I've heard, and I am a fan. She did a great job as Limelda Jorg in the
Madlax English dub. I'm pretty confident she'll do Teresa justice. Hopefully.
*waits for rabid Teresa fans to kill me* 
No listed VAs for any of the other characters yet, however.