Take a look at what a source known as "Jedi Master SQL" had to say.
"There is an exceptional level of work going into finding the right cast for the new films. Not only is the effort going further than any film in the history of the industry, but the real thought is going into the mix of the group and how they will look, interact and fit together. Every week I hear more amazing actors linked with the roles, and I feel that we will have an incredible cast when all is said and done. Just this past two weeks I have heard the names of Emmanuelle Chriqui, Alexis Dziena and Taissa Farmiga all linked with roles - all exceptionally talented actresses. Whether any of them are cast is still unknown, but if you consider the quality of the people they are looking at - you can see the quality of the effort."
While this insider wouldn't reveal any specifics regarding the plot, the source did hint that there will be a planet which has been previously mentioned but never seen on screen in Star Wars: Episode VII, which was added in the video game Star Wars The Old Republic.
"Star Wars The Old Republic has added a planet that has long been mentioned but never seen on film..."
"Back to the 'Big 3' - I have only seen evidence for one of them having signed. I am not joining the sceptics suggesting they are not all back, but I can only tell you what I know.
All things said, all of them have worked with Lucasfilm in the last few years in one avenue or another - and all bring something interesting to the mix. But you need something of substance to carry off having them back; otherwise it becomes an awkward task of making a meaningful cameo for them.
It would not surprise me if they did not all come back for Episode VII but maybe came back at varying points in the new trilogy. The script will determine their status, but the script must be story driven, and if the natural story includes them all I will be ecstatic - but I don't want a script to be written to ACCOMMODATE them all. If they are back, it must be of substance.
I would suggest that the whole principal cast would be announced in a group. It creates a natural shield of scrutiny for any young or new talent (or at least delays or spreads it out) as everyone has a mass of stories to write at once. Judging by the history of PR releases to date, this may be a simple black and white press release on The Official Star Wars Site with a photo of the group."
In related news, a source close to the production at Pinewood Studios revealed that the crew has already constructed a full scale model of the Millennium Falcon, which is supposed to be even bigger than it was in the original trilogy.
"A full-scale 1:1 Millennium Falcon has been built as well as the interiors of the ship for filming. The Falcon is done - inside and out. The sets were built off-site, ready to move when Lucasfilm/Bad Robot were ready to move into Pinewood."
Of course, nothing has been confirmed by Disney or LucasFilm yet, and it isn't known how this iconic ship will play into the story line.