To answer your 2 questions:
Overlord means there are more overlord type of monsters than usual. There are 3 main monster types in the game: overlord, legion, and talon.
No there isn't a way to disable the console, but if you accidentally bring it up ~ or escape will get rid of it.
Depths of Peril, Kivi's Underworld, Din's Curse, Drox Operative, Zombasite, & Din's Legacy