Q1) 'Calpers is the name of a person. The sentence means that Calpers was not convinced that Warren Buffet was independent in his position as a Board Director for Coca Cola.
Q2) This sentences means that in Warren Buffet's opinion, you cannot just look at a list of rules to decide if a director is independent, because there are other factors you need to consider, so you need to look at each case individually including these other factors and decide for yourself. When people use the word 'magic' as an adjective like this, they mean 'easy, without needing hard work'.
Hope this helps.