Yes, Gugalanna is Ereshkigal's husband and a god himself as well. Without Anu's permission there's no way Ishtar can convince him to go thrash Uruk.
Greek myth heavily borrowed Hittite/Akkadian/Sumerian mythology, so you'll see a lot of similarity / conflated story.
The Sumerian Gods Civil War against Tiamat is similar to the new Greek Pantheon vs Titan / Gaia's children wars