Norse beliefs, Similarity between the different Pagan systems

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Hi. I know that the gods/goddesses in Norse mythology are the Actual Gods but if i was to take it literately and be NORSE, would i still be working with the gods?I know that the Greek,roman,Egyptian and Norse gods are all incarnations of the Gods. Also, how did Norse beliefs come to the Vikings?Did pagans from other countries spread the message of the gods to the vikings or were the vikings living with the gods at one time (i know about the Golden Age BTW)
Also, does Valhalla actually exist? If the Egyptian beliefs are true for example, how can the Norse beliefs be true aswell?