Yes. In the end credits she sings "Hush little baby, don't say a word. Momma's gonna kill for you the whole damn world."
On Joker's fate - if it was two Clayface Jokers in the final fight, I'd say this is a Joker scheme to fake his death. Joker did say the only way to outwit the world's greatest detective was to be obvious, or something like that.
I've been grappeling around the city after the story, and you hear goons talk about Joker's demise. Interesting comments. One guy pretty much shrugs it off, saying he's died before.

t:
Bane's side mission was quite good. Just completed it then. The ally aspect was refreshing. As was the end fight team-up. Though this Bane continues to be a bit of a silly sausage. I don't really understand why he even told Batman about the Titan if he wanted to collect it all for himself.