“No killing” policy
The first two years of the Batman comics was a very confusing time for Batman (and the readers.) He didn’t just brandish a gun to fight his enemies, but he also killed his villains in a number of ways. During Batman’s first appearance he punched a criminal into an acid tank commenting that it was “a fitting end for his kind.” Maybe that’s why he was called the “Dark” Knight. The creators later opted for the “no killing” policy so Batman can keep his iconic villains around, to battle at it for years to come.
Gotham City, NJ?
Batman was original set in New York, like most of the comics of the time. Then writers decided that Batman needed his own turf, so they could give the comics its own world. Gotham’s exact location has been unclear, it was depicted to be on the East Coast, and also in the Midwest, but it was now officially stated in canonical sources that Gotham is in fact located on the East Coast, specifically in New Jersey. This fact has never been stated but there were a few instances that you could spot a “Gotham City, New Jersey” on license plates and once on a driver’s license.