Entertainment Weekly has released more interviews with the cast of Star Wars: The Force Awakens. The key piece of new information is a little bit of information on the character of Maz Kanata that is played via motion capture by Lupita Nyong'o (12 Years a Slave). The character is the big eyed alien standing next to R2D2 on the recent poster and has the line "I have lived long enough to see the same eyes in different people. I see your eyes. I know your eyes." in the trailer. Abrams says "Her history is that she was a pirate for a long time. She’s lived over a thousand years. She’s had this watering hole for about a century, and it’s like another bar that you’d find in a corner of the Star Wars universe." (basically she sounds like Guinan from Star Trek: The Next Generation). As for the poster, it was recently revealed by the IMAX twitter account.
Who is Supreme Leader Snoke? - Played by Andy Serkis using motion capture, the character is described as "...an enigmatic character, and strangely vulnerable at the same time as being quite powerful... He is large, he appears tall. And also just the facial design - you couldn't have gotten there with prosthetics. It's too extreme." That is pretty much it.
Where is Luke Skywalker? - Nothing revealed from Mark Hamill and JJ Abrams other then just saying keeping the surprise is good and the characters' are what fans choose to make them