What is the minimum length for the pendant light.

It depends on the amount of room in your wiring box. Loosen the nut at the base then pull the wire in. Including shade or light bulb you could make it less than a foot. You may need to cut some of the wire. Don't cut more than you need to cut to fit into the wiring box because you may later want to pull some back out to let it hang lower in the future. Be sure to retighten the nut at the base so the wire stays where you want it to hang.

wire can be shortened right up to canopy

There isn't really a minimum length. You could pull this light all the way up to the base if you wanted to. The length is controlled by the cord which can be pushed up into the base as far as desired (provided there is room in the light box). I had to cut some of the cord off of mine because the excess wiring overfilled the light boxes.

The cord can be fully adjusted so that the two decorative caps touch.