Not so much about the events and characters, since they must have some freedom there to make the show, and that would spoil it for me(i'm only in the second season).

But i'm interested in the battle tactics displayed in the show, the woman rigths (specially divorce rigths, was there some procedure? Minor spoilers but in the show Lagertha kinda just leaves after Ragnar is unfaithful. Was that common?)

And religion? In the first season they have some festival, with orgies and sacrifices. Human sacrifice is common. And they still belive in Odin and stuff, when did the Vikings adopt the cristian faith?