I just loosen the front sling mount, remove a screw just infront of the trigger guard and slide the rail forwards then slide the battery into the rear of the dd rail. more awkward than it needs to be but not too much drama really.
I don't know if the construction is different on the ICS or what but i find the gun to handle ok. But then i was used to carry the real steel for 6 years in the reserves lol.
I fiddled with the position of the grippod to suit my arms and find mine comfortable But i'm only 5'7 but fairly broad, but can imagine some guys who are taller or have longer arms would find it a tad awkward. Could move your grippod further forward and side mount your llm.
I got the spectre from patrolbase. Its locked to 4x on the optics, but you have the red dot on top and a ironsight on one side to boot.