can anybody inform us about long distance bus travel from hong kong to xiamen?

Well, I cannot find the bus schedule of this route.
Instead of taking the long-distance bus, you can pass the custom at Huanggang Port and take subway Longhua Line to North Railway Station. Then take high-speed trains to Xiamen directly. This way will provide more train schedules for you. They depart from 07:00 to 18:55. The travel time is almost 4 hours. In addition, the ticket fare of first class seat is CNY181 and second class seat is CNY150.5.