[@Dark Light] Co-GM here! I'll try my best to explain stuff to the best of my ability, and Kuro can chime in if I missed any important bits. c: 

1. The RP will mainly be following the WDL during the beginning of the roleplay, and gradually branch out to more and more groups as the story progresses. That doesn't bar people from making other characters, though, or those who might be considered antagonists.

2. Not necessarily, nope. I'm writing a Demon Lord, for instance, and it's possible to create a nonhuman character- although if you're hoping to make a nonhuman working within the WDL, keep in mind that the WDL is heavily anti-nonhuman. Illusion, Kuro's character, and the Seven are exceptions, but any other nonhumans would have to hide their true identities if they were working within the WDL. 

3. What do you mean by "demonology", if you don't mind my asking?

4. Characters can die, although a character death will only be performed with player permission, or if the player is absent and unresponsive for an extended period of time. It should be noted that if a character does put themselves into a high-risk situation, however, that there [i]will[/i] be consequences- although it should also be noted that death in T7C doesn't work as it might in other canons. I'll leave that to Kuro to explain, however. c: