Wow, great discussion on risk. The only thing I would add to the discussion is that before you try to model risk, you should read 'The Flaw of Averages', by Sam Savage - http://flawofaverages.com/
Put simply, any real risk model should probably avoid being a 'single number', but a range of probabilities. This models the distribution of possibilities much better and helps you make better decisions.
Put simply, any real risk model should probably avoid being a 'single number', but a range of probabilities. This models the distribution of possibilities much better and helps you make better decisions.