Hi Flygirl,
hong kong is one of the easiest airports to transfer out of. From the plane to the lounge shouldnt take you more than 20 mins thats including security. There are 2 cathay lounges that you can use as well as the qantas and ba lounge in hong kong. I prefer the cathay lounges. Lot of food options in the cathay lounge. If your stopover is 4-5 hours you can take the airport express to kowloon which is 22 mins on the dot and the frequencies are 5-7 min. There are plenty of shopping options at the airport as well if you dont want to nip into town. Hope this helps. safe travels!