As far as I know and have heard , the Group fly powers offer a -ACC. As for the Flight speed , I dont really know but when i have some time i will do a respec on the test with my PB for ya to find out.
Well personally, I'd forget these questions and respec G Flight out 
And yet... it's remarkably useful at times already. I can think of plenty of times in the game when being able to make the whole team fly would be very useful... various trials and TFs mainly.
Two questions regarding Group Energy Flight for anyone who has played around with it:-
1) Does it really grant the -ACC as suggested in the power description? I ask as the -ACC was removed from Fly a little while ago, and obviously it would be much more useful as a power if it didn't grant -ACC.
2) I've read suggestions that Flight Speed enhancers in this power only enhance *your* speed, not that of your passengers. Can anyone confirm or deny this?
Many thanks in advance for replies.