In Judaism, Satan isn't even a fallen angel. HaSatan, Hebrew for "the adversary", and source of the Christian Satan, is still an angel, who "is charged by God to tempt humans and to report back to God all who go against His decrees." Thus, he would definitely appear as an angel.
None of these. The bible says that Satan comes as an angel of light, he was once the most beautiful angel that God created. And still is. He isn't some scary monster now that he got kicked out of heaven and is creating havoc around the world.