Thanks for answers, I think I almost understand how it works
BTW - what's wrong with Tung Chung anyway? I stayed there during my interview (the Headland Hotell was full) and found it a nice place to live: close to the airport and Cathay City, well connected with downtown by the MTR (o.k. could be a tad closer), not crowded, lots of green stuff around... Am I missing something?