First, we can shake those pesky "not so much CGI and motion capture as just a silver suit" rumors. Weta is, of course, still involved, and plans on using advanced motion capture techniques very similar to those used to bring Gollum to life in the Lord of the Rings movies. The process has naturally been updated and advanced in the few years since, but the essential stuff is the same. Weta is good people, and I trust them to do an excellent job with the Silver Surfer.
Second, I am sad to report voice casting for the Surfer is not yet determined. Fans of actor Doug Jones, who will be inside the suit, continue to pull strongly for Jones to get the vocal work as well. Director Tim Story, however, has not ruled out a Hellboy** approach, with Jones doing the bodywork (Abe Sapien, in that case) and someone else providing the voice.
*Go ahead and tell me if you've got a different favorite, I imagine someone out there does.
**It should also be noted Jones will voice Abe Sapien in Hellboy 2.