The best place to start exploring Singapore from is the City Hall MRT station. From there you can ride to Chinatown or Orchard Road or Little India or where ever you want to go. The Station can be reached by going through the Raffles Plaza. The MRT is cheap and a means to move around much quicker than by bus.
The Marina Plaza shopping center has undergone a complete change in the last couple of years, and I hardly recognized it. There are several great places there for evening entertainment as well. The Marina Plaza is across the river from the Merlion.
Some of the best roti prata can be found down stairs at the IT malls. Whether you like it with egg or onion - it's hard to beat roti and curry as a good snack or even as a breakfast. Most of the small restaurants sell food - but not drinks. Usually there is one place that sells only drinks. Do try Ginger beer if you find it.
The garlic naan bread at the hawker squares around Queens is worth stopping for. Make sure you don't skip over the small places serving it and Indian foods while looking at all the other hawker stands. Chicken briyani is a great meal anytime of the day!