A-no. You can't unrestore cleaning. Book will forever be "plod". You could remove pieces, color touch and tear seals in theory (though you might be left with a mess) but you can't unclean a chemically cleaned book
B-see a (no)
C-yes. Definitely reverting back to days of old where resto is not as stigmatized.
The reason, I believe, that plods are frowned upon is that so many folks had, previous to cgc , bought books they were led to believe we're unrestored , only to send to cgc and unexpectantly receive restored grades. That's where the "purple label of death" came from. Restored books have always had value in the market, but this general "plod" mentality will continue to slowly shift back to more positive.