In interviews she isn't anywhere near as exaggerated in her demeanor or behavior than in her music videos. She seems much more naturally relaxed and composed in many of the clips I've seen of her, which would have me think IP > EJ. On top of that I don't get the same spaced-out tinge to her as I see in Ni egos. Compare her to someone like Janelle Monae, who I estimate is Fe-INFp:
http://www.youtube.com/watch?v=oFYou-c7HKE
http://www.youtube.com/watch?v=lkAHDFWtlPo
What you're saying about her being an "actor, thus ENFj" sounds like an appeal to a vague and highly interpretable stereotype, and I see no reason for any Fe subtype to be unable to create and implement personas in the same way. Sure she may be highly aware of her characters (I'd be astonished if she wasn't), but it's pretty clear in her live performances that she plays up these characters for laughs. If I could find a video of her recent performance at the Grammys I'd post it as such an example.