Airport Express Travel Pass is an Octopus Card with either one or two Airport Express single journey(s) plus 3 consecutive days of unlimited travel on MTR (except Airport Express, East Rail Line First Class, Lo Wu and Lok Ma Chau stations). The price is HK$220 and HK$300 respectively (with HK$50 refundable deposit). It is only applicable for foreign tourists who will be staying in Hong Kong for less than 14 days.

If you stay in HK more than 3 days, I think a normal Octopus Card is more fit for you. You can pay the bus A21 by the card.

It is generally safe travelling in HK, but you'd better not go alone at late night around HK.

You need to take bus A21 from the airport to the hotel instead of A27. Get off the bus at Man Ming Lane, Nathan Road, you can walk to the hotel then.