can my family of 6 ride the airport express from kowloon going back to hongkong airport? our flight is at 7pm so what time should we leave kowloon? where do we go and buy the tickets for return to hongkong airport by airport express. we have 6 big luggages too. how much is the fee for the adult and for the child? There are 4 adults and 2 adults. or upon arriving at hongkong, can we buy a rountrip ticket pass for airport express?