Okay, so some of these people are too old now to play the characters, but I'm going to pretend I have a Silver DeLorean so that age becomes something of a non-issue.
OBERNEWTYN
Elspeth: Alisen Down. She's a Canadian actress. Was in Mysterious Ways and a whole lot of Canadian stuff. Theme song: Frozen by Within Temptation
Lyrics /
YoutubeAriel: Tom Felton (Draco Malfoy) or Kieth Harkin. Okay, so he's a singer, not an actor, but... well, LOOK at him! *swoon* Theme Song: Some Like it Cold by Xandria
Lyrics /
YoutubeMatthew: James McAvoy You may know him from Children of Dune, The Lion the Witch and the Wardrobe, Attonement, Becoming Jane, and so on.
Rushton: Norman Reedus from Boondock Saints and Gossip. Dark, Broody, he's perfect. Theme SOng: The Cross by Within Temptation
lyrics /
YouTubeCameo: Evanna Lynch (Luna Lovegood from Harry Potter I don't think a picture is needed for her) Theme Song: Restless by Within Temptation
Lyrics /
YoutubeSelmar: undecided. I was thinking Rachel Hurd-Wood, but she'd be better for Dragon, judging from the pic I found. Theme Song: Overcome by Within Temptation
Lyrics /
YoutubeFARSEEKERS
Dragon: Rachel Hurd-Wood (Wendy Darling from the latest Peter Pan)
I will update this post as I fill in the rest of them.