NSEU:
BTW, if communications break down between the ground and flight deck during a critical part of pushback, what is the procedure to stop the aircraft? (at least with a tug, you can signal the tugdriver to stop... or even if you are in difficulty and are unable to signal the driver, he can see what you are doing at all times). Pushing back a 747, how long would the headset lead have to be before the pilots can see me? (Note: the longer the lead, the more likely it is put strain on the wiring, leading to failure... or to get caught under the wheels)... And just ask me how many times I have called the cockpit only to be told to "standby"....
It's all done on hand signals only! It's too dangerous to connect up for it. You have just run through why we used hand signals only for it. Can't you leave the practicalities about pushing to those that know about it, and stick to the technical side?