The stairs in my home have carpet over them and i want to take it off. The stair treads look to be in really good shape, at least the areas that i can see are. The carpet has nail strips attached to the treads. When i take those off what is the best product to use to fill in the holes. Then is there a way to stain or refinish the treads and landing at the top of the stairs to make the filled in holes disappear?