Hahaha, I shall update my own post. Just came back from my cruise.
(1) Plugs: Yes, you need an adaptor
(2) Inflatable bath tub: Yes, I bought one. Was very useful since my baby can't stand well and on his own.
(3) Water: No need to bring kettle. Provided in the room. Just bring a big water of bottle to store boiled water so that it can cool and you and baby can drink.
(4) Baby food: Bought some other brands of jarred food from other stores that mummies in this forum recommended as well as the Pigeon brand porridge. During the breakfast spread I also scooped some plain congee into his thermos to mix with the Pigeon porridge for lunch to dilute salt content in it.
(5) Baby cot: It's not a cot. It's a play pen. I took extra pillows to lay it into a mattress. I also brought my own baby bedsheet and blanket.
(6) Pram: Not necessary to bring to use on the ship. But it is useful when clearing immigration with all your barangs. When we got off the ship during shore excursions, we didn't use the pram. We brought a baby carrier.
(7) Medication: No need sea sick medication.
(8) Portable baby seat: Yes, I bought the Naforye cushion dining seat so I can use on any chair. Used this on the pool deck as well as in the room. Makes it easy to feed him and leave him to sit on any chair.
(9) Additional notes: Toiletries bag not provided in the room.