As Star Wars Episode VII is a JJ Abrams production, that means information will be hard to come by and what information you do get could be incorrect or just rumor. The latest is that actor Peter Mayhew will return as Chewbacca, joining returning favorites Harrison Ford, Mark Hamill, and Carrie Fisher. The reason it remains rumor is that the information has not been confirmed by Disney. Which doesn't mean much since Abrams has no problem letting false rumors circulate if it contains his movie secrets (which he defines as literally anything and everything to do with the movie, even if not really remotely related to spoiler information).
In other related news, Disney Studios Chairman Alan Horn said in an interview that Episode VII has already started filming. That doesn't necessarily mean the principle photography has begun. Chances are whatever is being filmed is background plating and other things needed for ILM to begin their CGI work on the film that probably started months ago and will continue almost right up to the film's release in December 2017.