Technically it's YHWH. How that's actually supposed to be pronounced is a matter for debate.
Not really. Only the Jewish High Priest knew how or was allowed to pronounce it, and only on Yom Kippur. And the last Jewish High Priest died 1947 years ago. But the approximate translation "I am, what I am" isn't far from the truth. Not "It is, what It is".
In Kabbalah and Aggadah, G-d has many names, each an archangel. In angelology ... John the Baptist being Sandalphon and Jesus being Metatron. In their angel forms they are seraphim ... fire angels.