victor
Stop wasting your time! you wont get asked why they choose a particular brand of engine. In the past cx used RR to keep its british ties... they want to know why you want to fly, how much research on the company you have done and how much extra effort you have put into pursuing a flying career. i have said it many times before, if CX wasnt offering this course would you be still pursuing this as a career??? with a 1 hour TIF you are on your way, but expect a question like, why havent you done more flying? with the lack of flying you have, you arent expected to know everything, read the book they send and understand what it is saying!
If you dont get through there are many ways to get there. you may even have to reach into your pocket and pay for a CPL. however, what you learn from having to fund your own license and the experience you gain from getting it makes the time, and money, spent all worthwhile!