Well, I will try and answer these the best I can.

For the Shoes - they are still called "Racing Plates" and there are a few different brands now days that are used. They are all made out of aluminum and some have no toe grabs, slight toe grabs, and 1/4inch toe grabs (the 1/4 ones are mostly used for QH races). Also, they have wedge shoes (which are slightly taller on the heel to give a horse more lift on the heel).

For the Surface - you are right about part sand part dirt. I am not sure of the percentage of this. They are now enforcing a new surface called the 'Poly Track', which consists of a 10-inch layer of a mixture of silica sand, fibers and recycled rubber materials. The mixture is covered with a wax coating that allows water to flow freely through the top layer to the drainage system below.