Question

I recently had wood floors installed and I wanted hardwood treads on my stairs. I removed the carpet from the stairs nad replaced some of the warped 2x12's by using flooring adhesive and screwing the replacements down. I'm working with dark walnut/mohogany stained oak treads as a replacement for the carpeting. I'm wondering what would be the best material for the decorative risers. I wanted to use white as a contrast to the dark treads. Is 1/8" eraser board any good with repect to durability or should I use some kind of plywood and prime it then paint it white. I'm not interested in seeing any grain on the riser. Secondly, should I install the treads first, then install the riser on top of the back edge of the tread or vise verus install the riser down to the 2x12 and slide the back edge of the tread down in front of the riser? Thanks for your assist