I have almost finished installing the 1/2" flooring and trimming it out on our first floor. I also want to install wood flooring on the second level and have a couple of questions.

How often does the flooring differ from one level to the next? In other words, if I want to install a different type of wood upstairs, would this look odd?

I would like to also install wood steps on my stairs. All that I have seen are 3/4". Is it possible to easily install a 3/4" stair nose at the top of the steps when also using a 1/2" flooring on the landing at the top? If so, How should I do this?

Are all stair treads 3/4" or is there 1/2"? If 1/2" is available, is it as sturdy as 3/4"?

Thanks