Yes! The output of the frequency inverter provides 3 x 230V, i.e., the motor windings are to be connected in delta. The power is maintained.
Yes! To be able to use the whole speed range, the motor windings are to be connected in double star.
When large centrifugal masses are to be decelerated the drive motor goes over to generator operation (oversynchronous operation). As a result, the current is fed back into the inverter and the intermediate circuit voltage of the inverter increases. The clocked discharge of the braking chopper limits the increase of the intermediate circuit voltage to a permissible value and thus prevents on the one hand the inverter from being shut down on faults and on the other it improves the braking effect.
No! Above nominal speed the torque decreases in inverse proportion to the speed: double speed = half torque!