Biscuits and cookies can be baked in bakeries or at home. Cookies made of oatmeal and raisins or with chocolate chips are probably the most common of home baked cookies.
Biscuits are NOT salty in the American sense. I have never eaten one that tasted salty. They are bread substitutes, especially in the countryside, and they are usually eaten with butter. In restaurants, biscuits with butter are sometimes served to people awaiting their orders. Cakes? No, they are not cakes. Cookies are pastries but not biscuits.