Pebbles are glued on to stop them falling off during shipping to the nurseries. It can impede watering and makes it hard to check soil moisture so best to take all that off the soil. Replace with unglued gravel if you want something but bare soil is fine too.
Ficus are tropicals so we do most work during summer when they are active. Repotting and pruning when it is cold can cause problems.
This tree has not been trimmed for some time. Ficus tend to keep growing long branches unless they are pruned. Later in spring you could cut all the long branches way back, even if that means cutting all the leaves off, and will be rewarded with lots of new shoots closer to the trunk where they should be.
As the others have suggested, use the time until it is warm enough to research and plan what you want this tree to look like.
In the meantime monitor soil moisture. The roots need to be damp but not wet all the time. Soggy soil can lead to rotting roots and death. There is no set watering regime because conditions vary through the year and soils and pots are all different. Check soil moisture by poking a finger into the soil.
All trees need light. Most ficus are trees of the jungles and rain forests so they can manage with lower light than many which makes them ideal for indoor bonsai but it will still need a really bright spot, probably near a large window but without getting too much direct hot sun in summer. Many of the growers here who keep indoor bonsai have invested in a grow light to give their trees even better light levels for better tree health.
Have fun on the bonsai journey.
. Any tips please, and remember I am a newbie.
it’s all good, the roots don’t look all bound up so you have time to learn a bit! 
