bus fare in Hong Kong

Hi would like to know how much is the airport express bus fare from the airport to Kowloon station and then to get the free shuttle K4 going to my Hotel - Empire Hotel would like to know if there is a certain time that i need to arrive to kowloon station because i'm going to arrive in HK at 2:30 PM . If in case i
will go by bus A21 how much will be the bus fare per person or in case i'll go by taxe can you tell me approximate fare that i'll need to spend. Lastly, from Empire Hotel going to airport where do i need to get aiport express bus and how much is the fare.