I want to transfer/direct my 10k unique visitors to - participate into my created - area51 proposed website category.
Who exactly are your 10k unique visitors?
Users will > define > commit > public beta
Isn't this a great idea.
Um, yes. That's why it already works that way. Users already define, commit, and participate in the public beta of their own volition.
Also, how can I gain monetary benefit.
That's not how it works. No one will pay you for proposing an SE site. You already have access to massive expertise and if your site launches, you will access to even more on a topic you chose. Isn't that enough?