Apart from hotel & flight.
how much money should i carry for fooding & shopping.
Usually SGD100 per person per day. But do prepare active credit card so that you can have extra cash in case.
100SGD per day per pax. If you manage on less - totally fine, but its wise to have smth extra in your pocket whilst traveling.
Depends on what you are going to buy : Cartier watches and Aston martin OR fridge magnets and Merlion snowballs?