It was vocally the best We Belong Together performance in years. Pretty sure the ending was all live as well, the long note was a bit shorter than the lipped ones and the part leading into it was different to any performance she's done before.
No, it was only once. The video on youtube has it on repeat
She said it before she was going to perform with Miguel, the one we all noticed, but I just watched it again and she said it when her dress popped open at the start as well