580EX II Speedlite or YN-568EX + YN-622C
Probably a bit late.
650D T4i makes full use of the YN-622Cs.
Note that FEC can be set using the camera button or flash menu or Quick Panel. It can also be set on-flash, when it becomes cumulative with camera setting.
By changing the 622s from Remote mode to Mix mode, you will be able to apply a wide range of controls.
YN-468II can be remotely controlled in E-TTL and Manual (but no HSS of course).
430EX can be remotely controlled in E-TTL but not in Manual, which is done by on-flash settings.
YN568EX is fully remotely controllable, with HSS. (No socket for battery pack.)
4 x 622s would be needed.
|IMG_8168ABCD by citori525|
|McKinley meadow by TimR32225|
from Natural meadows
|_DSC2146 by jerste|
from Helios-44 II
|Leopoldsteinersee by RaCor|
from Landscape - Colour #3