So, I was doing some googling and I found this, I hope it hasnt already been posted, so if it has Im sorry:
"It will have a real epic sci-fi story that involves this ancient battle that's been going on for billions of years and our crew of course ends up in the middle of that. It ends on a real sweet note and we'll be content with that if it's the last we ever do."
--David X. Cohen
An interview with David X. Cohen also suggests that part of the film will rely heavily on Fry and Leela's relationship.
New/comeback characters
Nibblers back!
Number 9 guy
Snoop Dog (or snoop dogs head I should say
and possibly Frieda Waterfall
Unconfirmed info
It is also implied in the commentary of Bender's Big Score that Bender's materials will cause him to melt in hundreds of thousands of years.
Thats all ive found so far