remoak, it's actualy illegal to ask for that information. You may require an applicant to be above a certain age and to have Australian residency, but you are not entitled to the specifics.
Marital status is totally out! An applicant may or may not be able to accept a basing or certain type of flying, but that is all you can ask. You are not their marriage councellor.
The only exceptions that I have ever heard of are some jobs that have maximum age limits, some jobs that require citizenship, and jobs that require top-secret level security clearances.
You may be sued if any of those questions are asked and the applicant is subsequently not employed.