Well, there are a huge number of DC comic characters. It's impossible to count precisely, but you can think of it as a vast and ever-growing collection that spans various universes and storylines.
It's hard to give an exact number as new characters are constantly being introduced. But there are thousands of DC comic book characters over the years.
It's hard to give an exact number. There are a ton of DC comic characters discussed over the years, and the count keeps changing as new comics are released.
300 isn't a DC comic. It has its own independent creation and doesn't fall under the DC Comics universe. The story and characters are distinct from DC's offerings.
First, familiarize yourself with the distinct styles of DC comic characters. Observe how lines are used to define muscles and contours. Then, practice with simple shapes to build the structure before adding details. It's also helpful to look at reference images from comics or online tutorials.
You need to start by understanding the basic proportions and features of children. Study some existing DC comic child characters for inspiration. Then, focus on getting the expressions and poses right to bring them to life.