That quest locks the Succubus out of your party permanently. She shouldn't even be in the castle afterwards. But this only happens if she is actually in your party when you do the quest. In the menu go to formation simply swap her out (click on her picture on the top, then either on another teammate on the list to the left or "remove") and only swap her back in when you are done.
The most info i know how to get about debuffs is to simply use them in a random combat and check what the icon says. But that can still be vague. A ton of statuses and buffs have been added to the game and as far as i know, nobody bothered to write a full list.