-That particular screenshot I always thought was a lens flare, not another sun. However, in the newer trailer there are some shots of Anakin and Ahsoka walking around on a planet that definitely resembles and probably is Tatooine.
-Funny, I never noticed the significance of the armor until you pointed it out, SilverWook. Guess we now know what happened to the plot point of Anakin gradually collecting the various pieces making up the Vader armor, which was rumored back before Episode III was released:
GL: "nah, save it for some future spin off."