Movement is NOT energy.At zero throttle and vehicle moving, the hub or a mid-drive tends to rotate ...
Q1 Is that energy utilized to charge back the battery or does it go waste?
So unless you brake with the motor, reducing the speed of the vehicle there will no energy generation.
Most motor controllers have the function of generative braking.Q2 If it is recovered then is that feature available in the motor controller?
So yes when the vehicle decelerates using generative braking most of that energy (60-90%) generated by the deceleration is returned to the battery.