I'm all about an OT bridge that deals with the Rebellion and such, but not so much with characters like Yoda, Han, Chewie, Lando, Luke and Kenobi. I love the characters, but don't want them to show up again until the old school films.
As for the founders of the Rebellion, that does have a lot of room. Leia? I can buy that completely. She was involved as an Imperial senator and was important to the story before ANH. Same goes for Bail Organa, Captain Antilles and the main droids. Show them as much as you want because that makes sense.
Empire? Of course Vader and Palpatine... and Tarkin would be fine too. And a ton of new moffs, senators, goons, etc. Stormtroopers galore.
Jabba? Sure, in a limited capacity. Though I think a new Hutt would be even better that has no relation to Jabba.
Boba Fett? I don't really care either way. Maybe a small role. But I don't really care.
I think that Lucas should look at introducing as many new characters as possible...Hell, create a whole new cast of main characters for the TV series with a main outcast Jedi, a smuggler or something, some survivors of the Confederacy that fight the Empire too, etc. Could even throw in Shaak Ti too. Love her.