According to Alan Horn, chairman of Walt Disney Studios, has recently revealed that the casting for Episode VII is almost complete, and some of it is being filmed right now. Though this filming is probably being done inside the Disney studios, either inside a set or in front of a green screen, there have been rumors that filming will occur in Egypt.
This would make sense because Egypt's desert landscape is similar to that of Tatooine, and considering Tatooine's significance in Star Wars (both Anakin and Luke grew up there), it could easily appear in the film.
Aside from Luke, Han, and Leia all returning for the movie, Billy Dee Williams is rumored for returning as Lando Calrissian, and Adam Driver is more or less confirmed as the villain. Unlike many of the Marvel films (Iron Man, X-Men, etc.) this movie has no literary counterpart that could hint at the plot of the movie; the plot is said to be original.
Though I haven't read extensively into the Extended Universe comic books and novels, I would still feel rather confused and annoyed if Luke married someone other than Mara Jade. Perhaps the movie will feature the same characters as the EU, but the storyline will be different, which I think would satisfy most Star Wars fans.
I'm guessing that many fans are hoping that Adam Driver will be portraying Darth Krayt, arguably the biggest EU Sith Lord. For those of you who don't know Darth Krayt, he was originally a human Jedi who befriended Anakin Skywalker during the Clone Wars. He survived the Great Jedi Purge (Order 66), and eventually fell to the dark side after being tortured by the Yuuzhan Vong. After that, he basically rebuilt the Sith Empire and reigned destruction on the galaxy. You can read his full biography here.
Hopefully, we will soon learn more about the cast of Episode VII, as well as its title and characters. Thank you for reading A Good Star Wars Blog, and may the force be with you all.