[Den]

Darkwing Duck is a tongue-in-cheek parody of what other cartoon?

Batman

What little girl (alongside her dog, Brain) helps her cyborg uncle fight crime?

Penny

Who is not-so-well-known for electrocuting an elephant to prove a point?

Thomas Edson. He did it to prove how "Dangerous" Alternating Current is, and to ruin Nicola Tesla's reputation.

Why did the Axis have difficulty using gas grenades along Russian fronts?

The weather was too cold.

Before he was erroneously known as Shazam, what was Billy Batson's superhero alias?

Captain Marvel (pronounced "Mar-vehll")