Hey Vanyh
Its a pretty small place. Express buses from Sing are good, but you could also drive down....its a nice drive. Your Lonely Planet would have given you ideas on where to go... Take a bike to get around the place, if you are not driving.
What I wouldnt want to miss in Mellaka is Jonkers Walk...amazing bargains on antiques, general knick knacks,home decorations etc. But do bargain!! Also check out the other markets near Hotel Equatorial...again good bargains on knick knacks.
Also dont miss a ride on the gaudy tuk-tuks....they are good fun!
Id just add Pulao Besar if you have another day to spare....Its not a GREAT beach, but its a nice single morning/afternoon destination. There are ferries that leave from the jetty there.
We stayed at HOtel Equatorial....quite ok.
Enjoy n have a great time!!