Does anyone know how the Rose, Orange, Fiesta, and Sugar Bowls were selected to be the only 4 BCS Bowls?

Because they wanted to join together to form the BCS. The Fiesta Bowl was a bit of a surprise but they had really spend most of the 80's and 90's pushing their way to the top of the heap. The Cotton Bowl was the big loser in that mix because they were the one of the "four major New Year's Day bowl games" that got left behind. I'm not sure that was because they wanted to keep the bowl as-is or if the Fiesta just got more important than them.