They need to be kept cool, below 22 C. This may be hard in Singapore; try to find the coolest room in the house, or place a bottle of ice in the tank each morning.
Axolotls are lazy and don't need much space. A ten gallon tank is fine for two. Use gentle filtration as they don't like current. They will appreciate flowerpots or other hiding spots. They will eat fish- or shrimp-based pellets, beef heart, and most small live animals up to the size of guppies or earthworms. Either leave the tank bottom bare or use gravel too large for them to swallow.