ATPL CPL or theory exam?
 

I have just attained my PPL in Australia . I was wondering if for my next theory exam, should I sit for the CPL thoery exam or will it be wiser to attempt the ATPL straight away.

I would also like to request for some information on the ATPL exam in Australia:
-When can I give the exam?
-Do U need to schedule it in advance?
-What's the cost?
-How many subject and if each subject has individual exam like CPL or is it combined?
-Is it a Computer exam or written?
-What and where can I buy the study material from?
-Is it possible to do it through self study?

Thank you.