I've used a different notation for AND ($A \cup B$) and OR ($A \cap B)$... is there a convenient notation for ``NOT $A$''?

Well, one notation for NOT $A$is $\bar{A}$, but I won't be using that, due to collision with ``mean value'' notation. Other notations one sees sometimes are $!A$ (often used in programming) or $\sim A$. I don't think we'll need to use this much in this class though.