Short answers, pulled from the story.
William Hyde Wollaston isolated rhodium in 1803. He dissolved the material in aqua regia and neutralized the acid with sodium hydroxide to precipitate most metals as chlorides using zinc.
Principal sources include South Africa, Russia, and Canada. South Africa supplied approximately 80% of global output in 2010 while Russian deposits lie within river sands of the Ural Mountains.
Volvo introduced the three-way catalytic converter in 1976 to reduce vehicle emissions because rhodium reduces nitrogen oxide levels effectively. About 80 percent of all global rhodium production goes into these automotive converters.
Rhodium catalysts drive hydroformylation processes that convert alkenes into aldehydes for detergents, fragrances, and pharmaceutical precursors. The Monsanto process uses rhodium iodides to carbonylate methanol into acetic acid.
Paul McCartney received a rhodium-plated disc from the Guinness Book of World Records in 1979. He held the title of history's best-selling songwriter and recording artist at that time.