Transport from Airport to Imperial Hotel in Kowloon, 15 persons w/ luggage. How much?

If you want a car to pick you up at the airport, I think you can contact the Trans-Island Limo Service Ltd directly. As far as I know, the pick-up service in HK is high.

You can take the airport express to reach Kowloon Station where you can find the free shuttle bus to reach your hotel directly. But in this way, it may be also a little costly. It costs 90HKD per person to Kowloon by Express Train.