How much should I prune my bonsai I would also like to repot but is that a good idea.

I think it depends on how you wanna shape it. You could draw a raw shape of the tree how it should look like when bigger and then you start pruning it towards that.
Pot wise from the pic it looks like the current put doesnt have holes at the bottom. Its important that the soil is draining

First of all ficus ginseng is not concidered a bonsai in the comunity. Bonsai is the art of growing a miniature of an old tree. Just take a closer look at your plant. Does it look like a tree in nature? There are a few peple that have tried to make one look like a mature tree. It involves some really advanced wood working and not all trees makes it. It is not impossible, just very hard to make ginseng ficus a bonsai.

Second: your ginseng needs to grow before there are anything to prune. If the tree is new to you, start by growing it wild for a year. Just focusing on tree health. Meanwhile look for Nigel Saunders youtube channel the bonsai zone. There are a few episodes on his Journey to make a ginseng into bonsai. Quite amazing stuff.