Thanks for your kind words.
I do try to get my head around these things but it's not easy. I've always found car and bike electrics a nightmare, and I work in electronics... :roll:
You're correct. The rectangle is the range of advance the CDI unit can cope with. If you used a timing light through the inspection hole in the crankcase cover you would see the right side of the rectangle at up to about 1500 rom and as you rev up the engine you'd see the rectangle apparently "moving" clockwise and the other side becoming visible.
The CDI unit is physically incompatible with others sold for CG clones, pitbikes, etc. Electrically they could possibly be adapted but you'll need to go head-hunting at Cape Canaveral to find someone to do it...