1. What is this? - knoppix-builder is a build system for knoppix. Creating a live CD based on knoppix should be as easy as "make all"... and now it is.
2. Is this another knoppix clone? - No. This is a system to allow you to create your own knoppix clone.
3. Why shouldn't I just use Morphix, Damn Small Linux, etc? - Let's face it. Knoppix is king. It's the most actively developed and has the best hardware detection.