(I'd say all that is easily possible)
I'd also say .. do you want things to be 'modular'?
or you do what things to 'connect' to a central 'brain' (so to speak)..
I think modular might be easier,, and produce the best results. (no wires running down the suit arms to the chest.. where everything 'connects to' for example.
pros/cons..
each 'unit' would gets its own battery pack and speaker though...
better sound effects IMHO if the repulsor sounds comes form the gloves, vs chest.
I can help you do all of these things. (and already have a face plate tutorial around somewhere)..
with wiring diagram..etc.
IMHO..
2 x repulsor 'circuits'.. (could be done with an Arduino Pro-Mini [$2-3.00 USD].. and some add-on boards.. depends on how you want it to work,,, trigger....etc)
1 x helmet circuit (eyes, faceplate/servo and audio).. another Pro-Mini and add-on audio board, battery/speaker..etc...
1 x body circuit.. not sure if you want to make the Uni-Beam/Arc Reactor part of this circuit? or how you want to control the 'flaps'.. but might require another Servo shield/board to control/power the servos..
not sure how you want to do the legs... but probably the easiest one to do? (least amount of work/components)