Hi Aussiehopper,
I can only go on what we are experiencing but if I were you I wouldn't be filling in forms just yet. We were anxious like you but our agent (Go Matilda) told us that some forms we thought were required were not (as they were going to do online app.)! Do start getting all your docs together for certification though as that will save time (we found it was much cheaper to do in bulk). You need a definitive list but will definitely need:
Birth certs for everyone on app. that need to be full ones inc. parent details.
Passports for everyone on app..
Marriage cert. where applicable.
Qualification/Prof. cert. docs for main applicant.
There are others but they differ depending on visa type.
You will also need proof of income in related job, curriculum vitae, letters of reference for work (again this may be visa dependent but all info on DIAC website I think) see link.
http://www.immi.gov.au/allforms/index.html
So much depends on your visa type and application method its difficult to be precise.
Good luck anyway,
Tracey.