Budget/Itinerary ideas for trip? Family of 4

Hi all,

I’ll be visiting Singapore with my family (spouse and 2 kids aged below 3)

We are there for 4 nights and are staying at hotel near Outram Road.

Flights/Hotels are paid for.. what’s a fair budget we should keep for food/conveyance - considering taxis/ tourist tickets etc? Also, is tipping a thing here?

For the itinerary, we expect to explore about 6-8 hours a day including transit but excluding meal time. What would be some kid friendly places? We will have our stroller. We’d like to do the aquarium, the gardens by the bay, the cable car.. but open to ideas from you wonderful people.