When I was younger, I remember someone asking the Rav of our shul if he can salt his porch, steps, and sidewalk on Shabbos (there was no eruv). The Rav said not only is it allowed, it’s REQUIRED!
I don’t believe that story. You are not allowed to do something dangerous (walk on ice) in order to claim pikuach nefesh. If it is pikuach nefesh, you should not go outside.
Mod 105: Rabbi Bodner’s muktza book says that Rav Moshe held snow is muktza. The shemiras shabbos quotes Rav Shlomo Zalman that it is not muktza.
I didn’t look them up, I saw it on some blog.