What are these "security questions"?
I've never seen them, nor have I ever been asked to provide answers for any.
When using the desktop QFF site, if you get the message about the SMS code, these questions pop up if you select the option that says something along the lines of "I need to validate another way"
From memory the questions are:
Date you joined QFF
Mothers maiden name
Postcode
DOB
You can choose any 3 of the 4 to answer.
Regarding the QFF SMS code requirement - one flaw in their approach is that sometimes international travellers will be using a travel sim in their phone, and will have no way to receive the code sent to their normal Australian number. This must be why they added the alternative of the security questions.
I might have access to roaming, but 99% of the time, I don't use it and turn off mobile data while overseas. The extra costs involved with global roaming mean I won't use it unless I absolutely have to (so much so that a few weeks ago an LAX airport hotel wanted a phone call to send out the shuttle for pick up - rather then be on a schedule - that instead of calling from my mobile and use roaming, I tried to contact them via the airport free wifi. When I couldn't find a way to do that effectively, I found a pay phone which was 10x cheaper then using roaming.)
A few notes here, because things have changed a lot in the international roaming space in the last few years, and it's not as bad as it used to be.
Data roaming is the expensive one, but this is a separate setting on the phone.
Standard voice and SMS roaming costs nothing to have active and is very useful.
It costs nothing for inbound calls/SMS. This is incredibly useful when travelling. For example, many frequent travellers use TripitPro, and this sends you proactive SMS notifications of delays, gate changes and so on. SMS is also very useful for various two factor authentication requirements (such as QFF, online banking), and sometimes airlines will send you updates via SMS if you have your phone number on the booking.
Also, calls to local numbers for the country you are in, are actually fairly cheap, especially short calls such as requesting a shuttle.
Alternatively, depending on your carrier, you can get full international data and voice roaming for as little as $5 a day that you use it. This gives you an allocation of free data, calls and SMS.