Overwatering and soil advice

I recently bought a 6 foot FLF and put it in a 12 inch pot at home. I didn’t disrupt much of the soil or roots to get it adjusted to its new space but I am guessing the soil is mainly peat?

Anyways, with the help of this sub I’ve learned its roots are wet and I should consider repotting.

Do you have a preferred soil type? I see FLF soil for sale on Amazon

When repotting, do you remove most soil from the roots? Remove all soil? Simply slip pot?

I’m familiar with watering techniques as I am a bonsai hobbyist but new to the indoor game.

Thanks.