Q6. Who is the richest person in the land?

I will answer this for the area around Candle Keep and for the whole setting.

The richest person around Candle Keep is Ponziano Camarata, the Merchant Lord of Greyport. He supplements his cut of the taxes collected from every trade caravan passing into the city with bribes and sometimes outright theft. He is a shameless man at heart, concerned only with keeping trade flowing to keep coins flowing into his coffers, though he tries to put forward a respectable mien to the public.

In the greater empires, it is an open debate whether Alcibiades, King of Mamm, or Shi Yang, Queen of Orochi, is the richest. Both rule the respective trade centers of their empires and both are known for displaying ostentatious wealth beyond the reckoning of normal folks.