My experience was that it was extremely rare for the expressway to be closed so you're probably fine on that account. My impression was that the expressway was well maintained. Do you speak Japanese? Like I said, occasionally there were signs saying that chains were required. I hung out with a lot of other English teachers and some couldn't understand signs like that and drove on the expressway anyway without chains and were fine... One of my friends also would often drive into parking lots via the exits because she couldn't read the signs! It's probably better if you can understand some basic road signs lol
In terms of scenery, I think the portion along the coast in Nagano can be scenic, but the Toyama portion isn't by the water and isn't too scenic. Especially in the middle of winter, I don't think you'll find the Hokuriku region particularly lovely, but hopefully I'm wrong