Hi ā This was very useful!
about the v+ from the output expander to the strip. the dashed red lines in the diagram.
The connectors i made for the expander 3 pin to the led matrix 3 pin JST each have all 3 lines wired up, in addition to the power feeding the panels and controller directly.
This extra v+ line is OK just not necessary? right?? Yes tell me i dont need to cut those lines after soldering them. 
Thanks!