Dick,
The lowest is Vmp, where the minimum power is needed to keep the aircraft flying. This is not Vs. It is a little bit above Vs, where it is difficult to fly, as you are on the wrong side of the drag curve.
In unaccelerated flight, Thrust=Drag. therefore the point at which minimum thrust is required (different from power, I realise, but as has been pointed out earlier, min power actually occurs at a higher speed) will be at the point where drag is minimum, e.g what you refer to as Vmd.
If you want to glide as far as you can then fly at Vmd
No, this gives you minimum sink. Max range is, as you state, achieved (in nil wind) at best L/D, but this is a different, higher speed to minimun sink.