Han
and
Chewie

Han and Chewie could be introduced in Episode III, when Han rescues a party of Wookie slaves, including.Chewbacca. As all of you know Wookies can get much more older than humans. (This is a very sensitive information since Harry pointed out that it could be wrong.)

Boba
Fett

Bountyhunter Boba Fett is going have a secondary role and if you believe the rumors he will be himself piloting the Millennium Falcon. Boba Fett will be a secondary character and the speculation that he himself pilots the Falcon remains to be one. His Copilot is pretended to be Captain Antilles, Wedges Dad. Boba Fett isn´t called Boba Fett at first and isn´t a Mandalorian either. While a huge battle with Jedi Knights, Antilles and Boba Fett split up and the Captain (Solo like Character)will square of against Fett, who is becoming a Mandalorian. (Same thing as the Han & Chewie news: very sensitive!)

Anakin
aka
Darth

Anakin Skywalker aka Darth Vader is in it too. He is definatly a (the) major character in
the prequels. At first he will be a young talented boy, who becomes an excellent pilot and
Jedi Knight under Obi Wan Kenobis Hands. In Episode II or at the end of I he falls to the dark side.

C3-PO
and
R2-D2

C3-PO is in it too, and R2 should be in the Prequels either.

Yoda

Yoda will be there as a computer animated character. Rumors i heard say that Yoda is
more or less a Jedi Trainer. He hasn´t fought for years and pushes all his energies in training Jedi Knights.

The
Queen

Princess Leias and Luke mom is in it, too. The character name is The Queen.

Cosmic-
beings

There are some strong rumors about a race of Cosmic beings (see Special FX section) but nothing specific, yet.

Jabba
the Hutt