I just created this account so sorry to bust in like this but this is the way I see it.
I think the actor and actresses for the movies/series would be best if it were unknown actors. Unknown doesn't neceserily mean bad ones. Orlando Bloom finished actors school just before he got his role in the Lord of the Rings.
Every time there is a movie of a certain story, for example the War of the Worlds. The movie, for me, fades away because of Tom Cruise. He is TOO famous. He is Mission Impossible. For me, he is Ethan Hunt, not Ray Ferrier.
If you use all those actors for the Wheel of Time, somehow you connect them to their famous storymovies.
For ex. If I would see Hayden Christensen as Rand, I would connect him to Anakin.
Also, there are many parts. In the first part they are mere farmboys. Not really experience demanding roles for neither of the characters. Their experience would grow in the making of the film, which would be both real life as the story.
So, if you ask me: Use unknown people to play the role, don't use famous actors, they will become the fa<e of the movie, not the story.