Real wood or engineered. Pre-finished is a good way to go. Clear is a higher grade of hardwood that has less variation in color and more uniform with less knotholes, so not as rustic and busy looking and less of a statement. Character grade has lots of variation and knotholes. It depends on your taste. I tried to find pics of what I suggested and couldn't find the right combo, but this pic shows the lighter flooring used on the risers to tie it in. This shows an interesting riser treatment. The tile could include both wood colors. This shows darker stairs with a contrasting floor that contains the stair color and other lighter colors.

Didn't see much that looked "modern rustic cabin" in your ideabooks. However, you should start with modifying the floor plan. I would close both the door and window to the kitchen in the foyer. That will give you a spot to hang a beautiful piece of art or a vintage/rustic textile like a native American blanket if you maintain the cabin vibe. Generally, the foyer should introduce you, your style, and set the expectation for what's to come in the adjoining spaces. I agree, the big window wall is probably supporting and would close up all of it except the width of a regular doorway on the "north" end of it. That will give you a nice TV location on the "south" end of it. If you don't plan for TV in this space and want the breakfast area to serve as dining, then just simply reduce the window to a centered 5' opening. With the breakfast area doing double duty you can incorporate the dining area as a bar for entertaining if you typically serve liquor. Begin with a 3-seat sofa and two chairs, a coffee table, rug, TV credenza, and floor lamps.

Why not stainless BTW is the cable to code where you are because not where I live. I am more interested in the columns can you post a picture

It seems like being in the same color family, they don't clash and won't look odd. I wouldn't replace them yet. If, after you finish the stairs and they look awful (which they won't) then you can do it. But I would wait and see how it looks. I don't think everything should be the same color. Then there's no contrast.