It's funny that people mentioned Rarity's personality going to opposite extremes, because I was thinking the other week that what really distinguishes Rarity from Pinkie Pie is that while Pinkie Pie just wants everyone to get along and gives people the benefit of the doubt, Rarity is more self-conscious and openly ego-driven, and she's much more likely to take things too personally. So on the one hand, being rejected by just one fashion expert is enough to send Rarity into self-exile, while on the other hand, compliments like those she received on her wings will really go to her head. Then you have Rarity seeing a stranger's fashion disaster as her personal responsibility to correct, and you have Rarity getting into tiffs with Applejack because she sees Applejack's straightforward approach as a personal insult to Rarity's artistic style.
But Rarity can also be flexible about this. "A Dog and Pony Show" had Rarity exaggerating this side of herself to make her look like more trouble to the Diamond Dogs than she was worth, while in "The Best Night Ever" Rarity demonstrated remarkable self-restraint in allowing the prince to definitively
prove he had a low opinion of her first.
I thought Kung-fu pinkie came from Dragonshy during the preparation montage, her weird fighting pose in the sunglasses.
I think I heard it meant "breaking the fourth wall", though what it reminded me of just now was Pinkie's rant from "Party of One" where she said "kicked me out of the group" and did a jump-kick to illustrate it. I guess the pony who loves to talk also practices plenty of pantomime in case she ever loses her voice.