The question was asked for Gamification, but I think it's a valid question for any proposal.
Should we prepare a number of questions and answers to seed the private beta?
No, part of the private beta is gauging how users are going to use this site in actual practice. Are there real problems to solve, and is the founding community the ones to build this site? If it looks like the site is filling with "seeded" problems folks don't really have, you risk making the subject look somewhat contrived and boring; something we don't really need.
I talk about this a bit in this post: Should we prepare questions before the beta starts?
But more importantly read through the post below (and blog post linked there) to understand the problems that can be caused by "seeding" content in a new community. It's been tried… a lot; and it almost never ends well.