Problem drinkers - and to be honest, if you did answer anything except "never" to the first question, then the AMA would define you as one and so would I - suffer from associated health complaints relating to kidney and liver function, as well as poor blood oxygenation.
It sounds as though the tests ordered are intended to scan for those things.
I don't see a problem.
If it's truly invasive, then lie, and know that at some point in the future a CASA inspector on a bad day will look at your Facebook profile pictures or photos of your bucks night, cross-check them against your questionnaire answers, and inform you you've committed a serious offence by making a false statement that could disqualify you from being a "fit and proper" person to hold an aircrew licence (and would certainly imperil your employment).
Your chosen course of action is one that you, as a rational adult, can probably decide yourself with no need for advice from the internet
