Short answers, pulled from the story.
The Iron Age began around 500 to 400 BCE in present-day Denmark and northern Germany. This period marked the emergence of Germanic languages and evolved under influences from earlier Scandinavian religions.
Thor was the most popular god among Norse people who colonized Iceland in the 870s. Place-name evidence suggests that Thor remained the dominant deity on the island while no place-names connected to Odin exist there.
Sacrifice or blót appears as the primary religious ritual in Norse religion with many texts referring to these practices. Adam of Bremen described a festival every nine years at Uppsala where nine males of every kind of animal were sacrificed and bodies hung in the temple grove.
Odin hung for nine nights on Yggdrasil to secure knowledge of runes and other wisdom in what resembles an initiatory rite. The term Yggr means terrifier and is a synonym for Oðinn making Yggdrasil mean Oðinn's Steed.
Danish king Harald Klak converted in 826 likely to secure political alliance with Louis the Pious against rivals for throne. The Danish monarchy reverted to Old Norse religion under Horik II who ruled from 854 until around 867.