Is there a general idea of approximately how much clear would need to be removed for the various forms of paint scratches like marring, swirls, holograms, RIDS, and such?
I'd say "no" to removing 1 mil of paint. I have an article here somewhere that I hand sanded and then buffed and documented after each step how much paint I removed and it was roughly .5 mils - so removing 1 mil would be unnecessary.
Then in conversation with the potential customer I would match my services to my customer as I explain in this article,
If they didn't understand my concerns I would grab the nearest Post-It Note have them feel it between their fingers and then whip out my handy-dandy iPad and show them this article,