How I can get from the Qingdao airport to Marine Holiday Inn? How aobut taxi? Is it expensive?

Airport line 1 is suggested for you. You can take the bus to reach the terminal and then walk to your hotel. It is about 600 meters between the terminal and your hotel. If you cannot find the exact way, you can ask the local people for help.
The taxi fee is about 80 RMB. Taxi is not suggested.