Your kid will be accepted probably if being invited or else there will be no interview offered at all. The interview is conducted in English, and the process takes around 45 mins as what 阿早! said. Vice-principal will observe kid's behavior while chatting to parents.
If accepted, you will receive a letter.
Very good experience in PN class, really strong in language. Kingston is carrying out IB curriculum from kindergarten. My son is going to it in coming school year, so maybe share later.