Spectacular Opening Ceremony

I'm just getting around to writing about the opening ceremonies of the Olympics - which truly left me stunned.
Anyone who has produced any event at any scale had to marvel at what the Chinese director and his cast of 15,000 pulled off. I'm still scratching my head that those rectangular tubes, so perfectly choreographed to music, culminating in the lovely wave of pink lotus flowers, were actually activated by humans! HOW DID THEY DO THAT????? I asked the same question when thousands of men doing Tai Chi stood in perfect formation with no visible lines on the field to mark their place. And don't get me started on the gorgeous film displayed on the upper scrim and on the field below. The entire event just kept WOWING me with Beauty.
So here's what I want to know - were the 15,000 cast members all volunteers, and how many hours of rehearsal did it require, and how did the directors communicate with them, and how did they get the timing and spacing so absolutely perfect, and did they have any choice but to be in this event, and did they have any idea how amazing it all was? I'm so glad I recorded the opening ceremonies so I can watch them again and again. But I'll never, I suppose, have answers to my multitude of questions.
The next time any of us has to orchestrate 10 people or 100 people or even 300 people to craft an experience, we should learn something from the Chinese about aiming high, about the power of beauty, about the pay-off for excellence and how inspiring it is to the human heart. And if you know any of the answers to my questions, or any of the backstory connected to this spectacular event, please fill me and others in. Meanwhile, my mouth is still wide open with awe...