i am going to make an attempt at some fanfic

i have tried in the past to create some sort of fan fiction, and it really didn't work.
so, before i make myself look really stupid, i need some things explained so if you guys could help, thanks!
-what does an exterminator do?
-what is a drac and what do they do?
-what is BLI?
-what is scarecrow?
-what exactly are zones?
-what do the killjoys do-just hang out in the zones? (wow that sounded beyond stupid)

(i have an idea about some of these, i just wanted to make sure that my ideas were correct before i started anything)

Thanks.