These stairs are wood with metal at the corners, and then this metal railing. We'd want them carpeted with potentially a different railing on there. Do you have to remove the whole railing or just the cap piece on the vertical post in order to do the flooring work?

Also, would you remove surface wood or just carpet over it? Is it very expensive to resurface stairs?

thanks for any advice!

Carpet is a covering...you don't need to do much of anything to prep, unless you're changing the basic stair design elements.

Hoosier: Typically carpeters just go over/around what's there. They'd probably pull up the base plate around the balluster, but cut around the actual balluster.

The other option would be to just run carpet up the middle, not over the sides and under the railing. But then those metal angles would be poking out the side. I suspect if you remove those angle you'll have an unattractive joint between the tread and riser.

It does cost more to carpet stairs than it does to carpet floors, for obvious reasons of labor intensity.