Take a look at this guide: http://lajollamom.com/things-to-do-in-hong-kong-with-kids/ You can consider buying tickets in advance to enjoy some discount. For example: Disneyland: https://www.klook.com/activity/39-hong-kong-disneyland-hong-kong/?aid=24 Big Buddha: https://www.klook.com/activity/45-ngong-ping-360-hong-kong/?aid=24 Happy planning!
DisneyLAND!! is definitely a-must-visit on my list. Foodie-wise I love dim sum there's a restaurant called Icon where the themed character dim sum changes every so often. The dumplings and noodles are amazingly good.
Disneyland and Ocean Park. Ngong Ping.