You can. Mine kept turning into glowing rectangles, so here the box, the grid and the flag are geometry Cycles actually traces. That's the whole idea.

It never changes unit settings, samples or Filter Glossy. It changes the render engine only when you click Switch to Cycles, and Clamp Indirect only when you click Set Clamp Indirect to 0. A setup can hide the subject's current lights and switch off ordinary Blender lights; it never deletes them, and Show All brings them back.

Yes. Distances and power follow the subject's size, so the light on it stays the same. Gear sizes stop scaling below 1/4 and above 5 times the reference size, so on a ring the softbox is relatively bigger and the light softer.

Often a softbox, stripbox or octabox standing between another light and the background casts it. Tick Let Other Lights Through on that light.

The CTO and CTB shifts and how much light they pass are LEE Filters' published values. Plus and Minus Green are a simple tint. The color itself is a blackbody color, not a measured filter, so treat it as a close starting point rather than a color match.