I know that Post Zero Hour wiped out the Batman and Talia had sex from continuity, as well as Joe Chill. But what about Crisis? Did anything change after that?

#1. Were Harvey Dent, Batman and Gordon all friends originally, or was that a retcon? Did Harvey and Bats know each other before he became Two-Face in the early days? Come to think of it, Two-Face has a pretty low body count. What issues has he killed people in?

#2. I heard that Killer Crocs origin was changed.

#3. The Batman origin seems to have stayed the same.

So really what were the changes? Thanks.