Here are the answers to the Spiderwick Chronicles Quest for Habbo Australia:

Level 1:
Question: "all can be known with a lens of *"
Answer: Stone

Level 2:
Question: "In the movie The Spiderwick Chronicles, what is the name of jared's twin brother?"
Answer: simon

Level 3:
Question: "Who plays the evil ogre Mulgarth?
Nick _ _ _ _ _"
Answer: nolte

Level 4:
Question: "What is the Director of the film's last name?
Answer: waters

Level 5:
Question: "What is the name of the item both sides of the unseen world want to possess?"
Answer: fieldguide

level 6:
Question: "In what does jarred originally find The Field Guide?"
Clue: c _ _ s t
Answer: chest

Level 7:
Question: "Timbletack is the house what?"
Answer: brownie

Level 8:
Question: "What does thimbletack turn into when he's angry?"
Answer: boggart

Level 9:
Question: "What is Hogsqueal distracted by?"
Answer: birds

Level 10 (final level):
Question: "What city did the Spiderwick family live in before they moved to Spiderwick Estate?"
Answer: New York City

They are posted in the following format:

Level
Question in that room
Answer to that question

So if you want to get into Level 5, the answer under level 4 is the answer.