My 17 yo is not in full time employment, but may be by the time we travel. Can I list him as a dependant if I buy a policy now?

You can list your 17 yo child as a dependant on your policy if he is currently not in full time employment, and you purchase the policy prior to him taking up full time employment. 

Dependants must travel with at least one of the adults listed on the certificate of insurance for 100% of the person travelling’s itinerary.

Cover is subject to the policy terms, conditions, limits and exclusions in the Product Disclosure Statement (PDS).