WHYB was not stopped from going into the top 10 because of the voice. The voice is probably helping it to get into the top 10. It was climbing anyway but now that the voice has cleared out the top 10 it should easily over take non-voice songs and then overtake the voice songs after.
#18 6 Voice songs above it.Train, The Wanted and B.o.B/Taylor are also falling. It better have a top 10 effect.
Radio is the most important form of promotion a song can get, but it's right that the add date might not help Where Have You Been much, in the sense that the stations that intend to play it would probably be beginning to play it by now anyway.
And with regards to features, they always count to the artist's discography if they're credited, like they've done for decades and decades now. Even if everybody hates Christina, nothing has changed. All of the songs Rihanna features on counts towards her discography, and Moves Like Jagger counts towards Christina's discography. There's nothing wrong with that, that's the way it's always been.