I think I know the answer to this but I just want to clarify. The 0 for Z axis is the bottom correct? and Z max would be when it is raised up all the way?
For installing endstops on Z I would tweak Z 0 with the router and tool in place just ever so slightly above the spoilboard, or is it just above the work surface?
Either way. It is usually best to set 0 as the work surface. You can choose in the software, estlcam I believe it is on the first settings page. I have videos using it both ways. zero at the bed is best for irregular work surfaces.