The Official Star Wars Youtube page has shared a Star Wars Rebels video! Executive producer Greg Weisman discusses working on Rebels, his favorite Star Wars movie, and how he made it in the industry:
Star Destroyers, The Wolf, and more:
Interior of the Ghost?
A good example of the index card story outlining method.
Stormtrooper concept art:
Character concepts. One of them appears to be a little Astro droid.
Pablo Hildalgo next to a clearer image of the Ghost concept art: