1. It's possible. Consider that 100 percent duty cycle isn't supported by usual high side MOSFET drivers, ins case you are implementing the discussed PWM scheme with a MOSFET bridge.
2. Free-wheeling PWM operation can be acceptable for IGBT or BJT switches that can't conduct reverse current, but causes excessive losses with MOSFET bridges which should be better operated synchronously.
3. The discussed PWM scheme isn't good for inverters because it can't drive reactive loads appropriately. Learn about two- and three-level modulation schemes.