So long you can speak cantonese/mandarin, read/write cantonese and read/write English you will be fine, they will of course test you on these. As with education wise, yes, you will be in tough competition. They will require Maths/English min. as stated on there site. If you require further details, I can ask my friend who is currently working as HK base. But most information you want about cx will be post on here, these another post about cx that you can read on.