Oy, this conversation has gotten thick and deep. Just a couple points of order about Batman since I don't know where to dive in:
In his early days he did kill (and carry a gun), but those comics are now not part of the "current" Bruce Wayne's history. However, he does carry a gun and shoot to kill the villain Darkseid in the recent comic "Final Crisis." His bullet isn't what ultimately kills the dark god, but that was his intention.
Also, saying the Gotham City PD is hopelessly corrupt isn't entirely correct. There's a significant amount of corruption, but whenever James Gordon is commissioner (as he is now in the comics) it's being rooted out.