To add to your last point pg stated more than once that the best outcomes for YC will occur if companies can make it to IPO. That's not a short-term play.
I think that the overall list of 'fastest companies to IPO' might be skewed by the dot-com bubble companies that were fast to IPO but failed soon afterwards thanks to having no real business model or income.
Not that I know of. Although it would only be non-YC companies (no YC company has IPOd yet - Dropbox and Airbnb are the likely candidates but Weebly has also hinted that they might be in a position to consider it soon)
edit: here's a link where he says as much http://news.ycombinator.com/item?id=265623