"Yeah, it would be great to have a No. 1 single and be a millionaire," Sky Ferreira says, without much prodding. "But am I going to change myself for it? No." The 21-year-old ascendant pop star has faced this dilemma since she was still in braces. Take a pop-by-numbers approach for a chance to be the next Britney? Or risk everything, and rankle her label bosses, by insisting on greater control over her music and image?