Short answers, pulled from the story.
The Old Norse compound word Ásgarðr combines the element meaning god with the element meaning enclosure to define the concept as the Enclosure of the gods. Historical texts offer various anglicized spellings such as Ásgarthr and Ásegard alongside Asgardr that reflect centuries of translation efforts from medieval manuscripts into modern English.
Snorri Sturluson describes the gods building a city called Ásgard in the middle of the world and identifies this fortified place with the ancient city of Troy. The text states that men call it Troy while the gods dwell there with their kindred and a high seat named Hlidskjálf allows Allfather Odin to look out over the whole world.
Ynglinga Saga places Asgard as a city in Asia based on an erroneous connection between words for Asia and Aesir. The saga describes Asaland as a section of Asia east of the river Tanais flowing into the Black Sea before Odin leaves to settle in the northern part of the world leaving his brothers Vili and Vé to rule.
Thor first appeared in the Marvel Universe within comic series Journey into Mystery issue #83 during August 1962. Following this release he became one of the central figures alongside Loki and Odin and makes his first appearance together with Loki in the 2011 film Thor.
Bifröst spans from the heavens to earth allowing the gods to cross daily for council and connects Asgard to other realms. Cosmology presents vague details where Snorri locates the homes of the gods in the heavens creating concentric circles while some scholars propose Christian frameworks influenced the organization.