Firstly, congrats to the new wave of applicants that have been invited to their stage 1 interviews. I myself have gotten through all the stages with almost zero hours.
As a guide to what to expect and how much to study for STAGE 1, here are my 2 cents from a zero hour applicant.
The JKI would be your first source of information, study it till its as familiar as the back of your hand. As mentioned its insufficient for your interviews, so you'll have to supplement it.
Book I found useful was "How to Ace a Technical Pilot's Interview". However from a zero hour point of view, quite afew of the concepts seemed quite foreign as well as it having close to 1000 qns?.. so use the JKI as a guide to help you narrow down to topics of interests. However, some of the answers are sometimes overly brief and therefore, supplement it further with other texts you can get your hands on or off the internet.
Study smart as well as hard.. Although this is a big opportunity and everyone that is going SHOULD study and mug as hard... Do it wisely as well... I narrowed down questions that are easy to ask verbally in an interview environment and worked on those..
You can find alot of common questions asked from this thread... Such as winglets, principles of flights, GPWS, flaps, slats.. etc etc.
Flying the Big Jets was another book I found that was a good introduction as it delivered concepts easily and was very enjoyable to read during my free time.
Be overprepared rather then under.
Broadly you should:
Study the JKI.
Supplement JKI with additional text.
Study about FTA
Study about Cathay's fleet and senior management.
Study about VHHH and YPPF
Once again, this is for a zero hour applicant, if you're a PPL/CPL holder, the expectations would be very much higher.
Best of luck.
