If we mine for the Lottery using our NastyFans user ID, how do we get payout for BTC shares mined?
You do not get paid for shares mined while participating in the contest. You are essentially mining for lottery tickets. The plan is to eventually allow both, but NastyPool development isn't there yet. If you want to mine on the pool and get your earnings without participating in the contest, you can still do so by using your Bitcoin address as your username.