Yes, as soon as you remove the engine... a whole set of big problems come with it... but the main safety functions operate without the engine, such as the air bags, crash sensors, ABS breaks, etc... so as long as you keep the "some" of the 12V system intact you're good to go.
Most of the sensors in the car is related to pullution control... and since the poluting engine is out now, most of the sensors can be removed.
yes, you can have the options of completly stopping the motor at a stop... I still can do that. but once you come to a stop, you will loose the power steering and AC... so I kept a slow idle to keep these systems going... I also did it because I love driving a stick shift.
it shifts exacly like a normal car.. no difference at all.
charging time depends how much you drain the batteries.. if you drive a lot, it will take a while.. but if you just go down a few miles, it will top it off in several minutes.
cost was about 14000 dollars... but i don't know the HP until my lab test come back... but it's like driving a 6 cylinder Aveo.