Re: Joker Knew of Bane's Existence.
The theories of the OP hold some truth.
But I do not think Joker meant or was referring to Bane. The writers did not even know Bane was going to be the villain in the conclusion.
I just think the points he OP made were foreshadowing the 3rd installment. The Joker could have been referring to other potential enemies. Twoface was suppose to be the third villain the Joker meant, maybe the Riddler.