If you mean binding, I prefer dark binding because it does not show dirt as easily. Any dark brown fabric that blends with the browns in the top would work.
I would NOT add a ruffle to the quilt. It would add a lot of weight and bulk. Better, in my opinion, to add a separate ruffle to the mattress if you want a matching ruffle.
For a quilt like this, I would machine sew binding to the front and hand sew to the back. The only reason to sew binding to the back is if you want to machine sew the binding to the front, which wouldn't be my first choice for such a beautiful quilt. The first method creates a nicer finish unless you are extremely accomplished in adding machine bindings.