[bootload]

"... You need to be prepared for tough questions. ..."

I think the point of the exercise is to really nut out the obvious questions. But how do you practice answering tough questions?

Reading through the posts here on prospective YC applicants highlighted the need to be able to think on ones feet. The number of questions fired at you is high. The best idea I can think to simulate this is be using skills developed by comedic improvisation.

Earlier this year at an un-conference ~ http://www.flickr.com/photos/bootload/collections/7215762254... the best session I went to was a entrepreneur/hacker who is also a comedian. Dan ~ http://twitter.com/danwalmsley explained that by play acting ~ http://www.flickr.com/photos/bootload/4031549850/in/set-7215... meant each person could act and re-act real time. This is a skill that could be practiced post RAQ and as you correctly point out, a place to answer tough questions.

[alabut]

"But how do you practice answering tough questions?"

And how do you handle answering so many of them, fired at you all at once from multiple people in the span of 10 minutes? Every description of the YC interviews says that's the hardest part and I can see why, for the same reason that grad students say that defending their phd thesis in front of a panel of professors is one of the hardest things they've ever done.

[bootload]

"... And how do you handle answering so many of them, fired at you all at once from multiple people in the span of 10 minutes? ..."

I don't know. I'd say learn to identify the questions you can answer as best you can. This is what I mean by having some form of roleplay, verbal, improv skills. Pick the Q's you do know, pick the ones that are important to your product.