(1) Megatron is not returning in the sequel.
Hard to say. I don't think Starscream will be leader if anything. Not sure about Megsy though... they did kind of ruin that.
(2) There will be a 7 team Constructicon team that forms Devastator.
It's possible there will be a team in the movie, but there probably won't be toys.
(3) There will be an Aircraft Carrier Transformer.
I don't think so. If they aren't using size displacement, this transformer will just be too big for the screen.
(4) 'The Fallen' from IDW Comics will be in TF2 movie.
I hope so, but it wouldn't appeal to an audience at large :\
(5) Optimus Prime gets a trailer, which combines with him to form a super mode.
I don't believe this for a second. Too gimmicky, and if there was going to be a super mode anything it'd be Magnus.
(6) Megatron gets brought back to life by Optimus Prime.
Maybe? They are brothers apparently.
(7) Starscream returned to Cybertron to gather more troops and then heads back to Earth.
I think he definately went back to Cybertron at least.
(8) Grimlock will not be in TF2 movie because dinosaurs can't be worked into it.
A character representing Grimlock (in attitude) will probably appear, but dinosaurs I think not.
(9) Scorponok returns for TF2 movie.
Maybe for a Cameo, but I dunno, he kind of needs Blackout to be important.
(10) Jazz will also return.
I don't think we've quite seen the end for our plucky little lieutenant
(11) A set of Twins are introduced.
Sideswipe and Sunstreaker for sure. I could believe this.
(12) Soundwave will definitly be a character in TF2.
In some form, just nothing like a tape deck :P
(13) Megatron will be brought back as Galvatron.
Nah... if Prime is back Megs will be back as "Megatron"
(14) One Transformer turns into an Ice Cream Truck.
Doesn't seem marketable :\