I would like to know all that too;-)
- This would need some time and extensive access to the blockchain to get the necessary information out. So far, I haven't figured out how to access it directly (and I'm not sure if I have the necessary skills).
- I am planing to examine that. I think this can be drawn out of the daily stats by @arcange.
- I don't know the YouTube ratio, but in poker and sports betting about 5% make money and the rest funds them. I guess that is a "normal" distribution. If you apply these 5% to Steemit, it actually looks not that bad. But then again: This is not a gambling parlor.