The claying is going well (on lunch break). Some observations:

I got a fair amount of light grey material off the (white) hood and roof, but am getting almost nothing visible from the fenders, doors, and quarter panels. Is this typical?

The included quick detailer spray, used as a lubricant for the clay, smells familiar ... like a weak version of an institutional cleanser (e.g., school restrooms). Know what ingredient the chemical odor is from?

Use your dominant hand only for rubbing with the clay -- it's way too easy to drop the clay (a disaster) with the other. I mold a handle out of part of the clay to hold with my thumb which helps too.

How long is one 50g lump of clay supposed to be used? I'd be inclined to toss the first one after this initial job. Another is in the kit.

Are there mail-order/discount sources of extra clay bars, only?