You should be!!
Search for Ding Ding trams--on and off for 25 cents each time--I'm sure you can find sushi many places but while I love it, I had more to eat in HKG than japanese food.
MTR is great--get the Octopus card (as mentioned above) You can use it for mass transit if you get it in combo from airport. Take a serious look at HKG tripadvisor--it is one of the BEST travel forums I have ever consulted/trusted.
When you're done w/Octopus, get you $ back less small deposit.
Use ATM's for exchange.
Once I get settled, I' can be a cheapskate. Avoid the big malls for food and ask about food courts/hawkers. I had no interest in the big attraction like the cable cars, but side trips on bus to maybe Aberdeen or similar would appeal. MUST DO--Star Ferry as ride--tres cheap--not $$ for "tour" either. USe Octopus card to pay!
See flower and/or bird market--as well as major night market in TST--Nathan Road madness..
I'm sure Nick can add plentyy!@
Subway is fasted way and if you have time, see that nunnery and 10,000buddhas. Super cheap--easy and fascinating sights--real HKG.
PS--bus to Robinson Road and HKG zoo (not big but interesting) and gardens. Walk back.