According to the constitution the only thing that you are required to tell the census taker is the number of people living in your home.
Period! Of course they my then threaten you with all sorts of legal action.
As I understand it there are two sets of questions, a short form and a long form. Most will get the short form. For those lucky ones that get the long form they will be asked questions like:
How many toilets do you have and are they low flush?
Do you own any stock? If so how much?
What is you yearly income?
What time do you usually leave for work? (yes that is a real question)
I believe the real goal here is to train you to answer any question that our master might ask without first even questioning the question.