I always loved Red Buttons. He was great in movies like "The Longest Day" (" Loud and Clear, sir!" and the Poseidon Adventure, but he was also great on all the TV shows I remember from when I was a kid. He'd be on Johnny Carson, Dean Martin, even Laugh-in. A funny, Funny guy, especially for an old guy. The Times did a nice Obit for him, and it's worth reading.
So is the plan to introduce the Joker here and Batfleck in SvB and then build to the two of them facing off at some point down the line? That seems a little backwards to have Batman v Joker III as the main event with Superman v Batman on the undercard.