Regarding VFD and old switch. You should be able to connect the old switch to two of the VFD terminals and programme the VFD so that it starts and stops the motor when the switch is closed. Just stops you having to push the tiny VFD buttons. I did this and then mounted the VFD in an old Tupperware to keep the dust out.
F.
Ps yes the VFD generates heat etc etc but even on my 2hp planer after 30mins of use it's still barely warm inside the box.