1. If I have played n tournaments with a ROI of x, then how do I calculate the probability of my real ROI being somewhere between x - a and x + b?
I guess it will have something to do with standard deviation which will be dependent on field size, payout structure, playing style etc. How can I quantify all this?

2. If my monthly expenses are x, then how big of a bankroll do I need before becoming a professional?

3. In ten years from now, what will poker be like? Will NLHE stay as the most popular game? Will there be enough bad players to earn living from or will the poker boom fade so that only decent players remain?