Are the following hadiths authentic: "The Messenger Muhammad saw during the Isra and Mi'raj an army of Allah in the fourth heaven that has no beginning and no end," and "An animal from among Allah's creation, its bite is equal to the seven heavens and the earth"?

The Hadith of the Mi'raj (Prophet's Ascension) proves the multitude of angels by mentioning Al-Bayt Al-Ma'mur (the Frequented House) in the seventh heaven, where seventy thousand angels pray every day, never returning to it after they leave. As for the existence of an animal in the shape mentioned in the question, there is no original source for it.