Flying into Hong Kong is easy. Immigration and customs a breeze on each arrival. Limo, taxi, or train are all reasonable routes into either Kowloon or Hong Kong Island. I chose taxi last time as hotel wasn't on airport train line and there were two of us. Previous time we arranged a smal bus as there were four of us and lots of luggage. If on your own, I would recommend train.
When leaving HKG, be careful about carry on luggage. What passes as standard 22" rollaboard in US will not pass muster. I had to go back to check in counter and have agent give me a special tag so I could make it past the check point.