No, Action Comics is a comic book series published by DC Comics. It didn't become DC Comics. DC Comics is a larger publishing company that encompasses many comic series, including Action Comics.
Well, typically, these action figure sharks from comics have sharp designs, articulated joints for posing, and could be based on popular comic storylines. Also, they might come with special features like light-up eyes or removable parts for added play value.
There are a ton of Batman DC comics. Different publishers, storylines, and reprints make it impossible to say exactly how many. But you can bet it's a huge number!