[Erniee]

The product and acccessories from menards should work just fine. You can run the wood all the way to the slope. You can add the same wood to the slope- if it is flat and then use a T moulding at the joint of the slope. At the stairwell, you can get a stair nose trim and trim it out like the metal that is there. On the stepwell walls, you can add wood there on the walls and the step risers, if you like. I sometimes do that or add some stainless steel sheets to the risers. For treads, I like Roppe rubber raised round stair tread. I install the treads last as I like that material to fit tight against the wall.
I believe 200 feet would be a safe figure. If they have lots of stock, then if you need more you can select from the same dye lot. Of course, you can also return any unopened cartons. I always like to figure long, in case some of the product has defects. The product is wood and sometimes flaws get thru past the inspectors. Ernie