What sort of Ficus did you buy? Many in Ficus family like being in smaller pot and repotting is usually recommended in spring when the plants have they most active growth period coming on.
There should be enough room and nutrients in the pot and compost for now and perharps you could use larger pot just for looks...sinking the plant into it with its current pot and support it with some stones and some on top too to hide the 'real' pot.
As for the compost..normal multipurpose should be fine and you plant should not need fertilizing for weeks after that.
Baby bio is good general fertilizer for houseplants..particularly those non-flowering types. Look for any 'houseplant feed', some brands do specify if it is meant for flowering or non-flowering plants.
