Is the $180 hotel price US$? Is there an additional service charge (and tax)?

I agree with the advice to use the train to/from the airport. You can take a wheeled cart (from the baggage claim area) onto the platform, although I'm not sure whether I've ever seen people actually take the onto the cars in the train. At Kowloon Station, the RC is pleased to send bellmen to meet your train, handle your luggage, and escort you (walking through the indoor shopping mall) to the hotel. When you leave, again hotel staff will take you and your luggage to the train, no problem.

There are also free carts at Kowloon station that you can leave at the entrance to the RC or W Hong Kong; people do this all the time with lots of luggage, although it helps to have the escort (at least the first time) as it's easy to get slightly lost in the mall. BTW, it's very convenient to check in at Kowloon Station (anytime the day of your flight, even for flights to the USA on USA carriers, but have the hotel concierge verify the details) and check your luggage then, so that you don't even ahndle it on the return Airport Express train to the airport.