The number of DC vs Marvel comics is quite variable. It depends on various factors like publication schedules and crossovers. However, it's safe to say there are dozens, if not hundreds.
It's hard to give an exact number as new comics are constantly being produced. But there are a significant amount, probably in the hundreds or even thousands.
No, they haven't. Making a movie that combines characters from both Marvel and DC Comics is a complex process involving rights, creative decisions, and potential fan expectations. So far, such a project hasn't come to fruition.
Well, 'Marvel vs DC Crossover Fanfiction' has a lot of gems. 'The Secret Wars of DC and Marvel' is a cool one. It takes elements from both universes' big crossover events and twists them in a unique way. It's full of action and unexpected alliances. Also, 'Superman in the Marvel World' shows how the Man of Steel would fare in the world of Iron Man and Captain America, which is quite fascinating.
First, you need to know both universes well. Read a lot of comics from Marvel and DC to understand the characters, their powers, and their personalities. Then, come up with an interesting concept like what if the X - Men had to team up with the Teen Titans? Next, focus on creating a good plot that keeps the readers interested. Don't just rely on the cool factor of the crossover.