Can you tell me more about roaches?

Where do they usually live? What do they eat? Is it true that they only come out at night and when everything is quiet because they fear humans? And then.....i'm gonna do some urban exploring with some friends and a friend of mine is very scared of roaches.....He isn't simply disgusted by them as many people are, he's scared as hell of them....he loves urban exploration but is his phobia an obstacle for this hobby? Can he solve the problem and if yes how? Are there many roaches in abandoned buildings or do they more likely live in sewers?