Thanks all. I am electrically "challenged" at best. I'm fairly sure I came across Steelbikeguy's extensive write-up on another forum, and understood nearly none of it.

As to compatibility, I'm pretty much stuck with Supernova. The lighting system is fully integrated into the frame. The wiring for the tailight runs inside the tubes, and the tailight mount itself was hand made just for that model. So the newest Supernova headlight model will supposedly be delivered today - and I got the one meant for upside down mounting this time...