Regarding bonus points... I would think it best to keep the number points consistent across all rounds, so everyone has the same chance to earn points. If you have 5 points available in one round, but only 1 available in another, there's a lack of balance there. You could make 5 bonus points available every round. For the chick round, since you can't give it to best use of the theme, I liked Stads' idea of the 'best female voice' (ie, regardless of quality of song). Dish out 5 points, which may or may not be 5 players, since the same act could be used by multiple players.
Just my $.02.