Once you turn in your paperwork (i.e. copies of your license, etc.) the CAD will send you a letter which describes your license conversion terms. CX will coordinate all of this. This letter will tell you which exams you need to take--you'll get "credit" for some based on your license and have "required" for the others--these are the ones you need to take and will probably be about half (Human Factors, Aviation Law A and B, Loading, Air Frame Systems, Electrics, Performance, etc.). They may send you to Adelade for a week or so for some instruction for the exams depending on your background, or a disk of study material (don't know exactly which). Also, you might be scheduled for a few classes at HKG to prepare you for the exams. In any case, you'll receive information which gets you ready for the tests and I wouldn't study anything until you get the CAD letter and your training plan for the exams. You'll receive your class/exam schedule as part of your induction at CX, then take the exams, pass, and press on to the conversion course. Depending on your flight time in civilian aircraft, you also might be issued a commercial license with upgrade to ATPL after 500 hours in multi crew airplane.
Good Luck !