some great suggestions so far.
My fav thing to do there is go to Central, it’s a buzzing scene late night and they have this series escalators (out door ) that allows you to walk from Central to some of the outer edges of Hong Kong Island.
One of those things you have to do to believe it and its a great way to get a feel for Hong Kong.
Love that city I envy you.
oh and an Octopus card to get around (it’s like a smart trip card but you can use it on buses, trains , some cabs and trams ) It’ll be your friend and I’ll bet a great souvenir to take home.