As to the first question about the current for the spur, no idea. I am not aware of any seperate fuse for this so I guess it's just a matter of checking the fuse for the ring downstairs.

Each work area has an extension lead out to it and I tend to make sure I'm only using one area at a time anyway. All that would be running would be the CNC kit including computer, though what I mean by "kit" is vague I suppose. VFD, steppers, water pump seem certain. Dust extraction for wood, coolant pump for metal are nice ideas but unlikely just now, some airflow into the planned enclosure is likely though.

As for other comments about lights dimming on startup, is that a feature of a particular piece of equipment and can it be avoided?