The written test should include three subjects: language, mathematics and English. I took the exam in 2008. Mathematics is just a matter of arts and sciences. Both are 100 points. It's basically high school stuff.
Be sure to introduce yourself in the interview ~ 1 minute. China people. That year, I was three teachers to one student. Then draw lots twice and choose one of the questions to answer. You can search CUHK's website. It has published last year's interview questions. There is a lot of room to play. In fact, the teacher is friendly. Just sit and chat ~ ~ Don't be too nervous, just be polite and confident.
Good luck!