The questions feel like tricks to get the entrepreneur to reveal negative information about himself or his company that he wouldn't otherwise reveal. If I were an entrepreneur sitting through a round of questions like these, I would be a bit offended. I suppose for a fledgling entrepreneur who actually may not have thought everything through, these may be appropriate. For everybody else, I'd skip them.
"2. If your equity/salary was based completely on the accuracy of your projections, what would your forecast be?"
Is it even relevant that the entrepreneur be able to make accurate predictions? Shouldn't you just focus on making stuff people want? And isn't speculating on how the size of company X the VC's job anyway? I bet Larry and Sergey didn't see Google getting THAT big on day 1.
It's less about the actual forecast and more about the way someone thinks about the business. If someone adamantly believes they're going to be a billion dollar company in a couple of years, that would be a signal. Either it's a really, really big idea and they're super-ambitious -- or, they're being unrealistic.
What has worked for your company? What did you do to retain the best possible people?