To get to CP Kobe, first it would be most convenient to take a limousine bus from the airport to Sannomiya.
If you do not have a lot of baggage with you, you can then take the subway to Shin-Kobe which is one stop away. It may be better to take a taxi if you have a lot to lug around though.
Dunno about the hotel rooms or how it treats Plat. members as I haven't stayed there... I live in the area so my own bed is much more comfy