Salam Norrizan, the fondant should be kept at room temperature, and not in the fridge. Usually if you work in an aircond room, and the weather is humid (mcm musim hujan..) it will sweat once you turn off the aircond. Just wipe with tissue and leave it to dry naturally. Yes it is ok not to cover with marzipan. Just use a layer of fondant and make sure the thickness is the same for all surface, usually not more than 1 cm thick. Depending on your cake, kalau kek tu kronik (penuh lubang or tak rata), just thicken the fondant. thanks !