How much do the Heroes and Traitor need to reveal while using their haunt-specific rules?
For a more concrete and official answer, this is from the Wizards of the Coast errata page for the game:


  How much do you have to reveal about what you are doing to the other side?
   You should announce the purpose of any action you are taking to the other side -- for instance, "I am making an exorcism roll now," or "This roll is to see whether the house blows up." You don't need to reveal what number you need to roll.