Will Vader appear in Rogue One?

Now that it has been confirmed exactly what time the galaxy Rogue One: A Star Wars Story is set, I have several questions.

The first blog I wrote about Rogue One I stated that I really hoped that they would set the movie in the time of the new trilogy, but now it is known that Rogue One will take place between Episode III (Revenge of the Sith) and Episode IV (A New Hope). This shows us that Disney is really looking to expand the Star Wars Cinematic Galaxy.

Here are my questions...

1. Will Vader appear in Rogue One? - The rumors have been flying since July that the ultimate villain will make his evil reappearance in this film. Last time we saw Vader on screen he was crying over the loss of the love of his life. When I was a child Darth Vader was scary and intimidating. I really hope they redeem him and return him to his roots.
2. What other old characters might appear? Tarkin, Bail Organa, Ezra, Kanan Jarrus and many more have the potential of showing up in this movie in some form or fashion. There are many characters that are known during this period of time.
3. Will we see any of the big 3? We know that Luke, Leia and Han are all around during this period of time. Luke is probably the most unlikely. A younger Han or Leia might make an appearance. Leia seems to be the most likely, especially if Bail Organa is included in the story. 

The premise of the film is "Following the foundation of the Galactic Empire, a wayward band of Rebel fighters comes together to carry out a desperate mission: to steal the plans for the Death Star before it can be used to enforce the Emperor's rule." At D23 it was said that this film would focus on ground war and truly be a "war" flick to show the struggle of the rebel alliance. It has been said that it will approach this conflict in shades of gray and not quite as black and white as the original trilogy. 

The film is set to hit theaters on December 16, 2016. I am holding back my excitement for Rogue One until Episode VII has hit theaters. I believe it will be very nostalgic to revisit the galaxy during a very familiar time in history and see the classic storm-troopers, vehicles and hopefully villains. This is a very exciting time to be a Star Wars fan!