The drop is EVERYTHING. Overall as a song though, it's lacking in areas. I would have liked more of an actual chorus and I feel the drop goes on far too long. Regardless, always nice to see her playing with her formula's and sound.
No, a demo version of "Swine" leaked prior to ARTPOP's leaking (same thing happened with Aura), and it had a longer intro. There's also a demo version of Pitbull and Ke$ha's song "Timber" which had a longer intro.