I think you might be reading a bit too far into Ragnar's "omniscience". In previous episodes, they made it clear that Ragnar was unsure of Paris' defenses. He even asked Athelstan about their defenses, but Athelstan replies that he hadn't paid attention. Ragnar, knowing that he would essentially be going into the…

I'm almost certain that Kalf (Kauf? not sure how to spell it) actually wants to piss off Ragnar. That talk near the end where he was talking about how he desires fame above all else… What better way to achieve fame than to kill Ragnar Lothbrok?

Yeah, I have to agree. I'm not really digging the supernatural vibe here. I'm not against having the supernatural exist, but bringing it to the forefront like it was this episode is a pretty big change. I hope they'll tone it down a bit in the coming episodes.

I absolutely love Wardruna. I wouldn't worry too much about them not being in this episode though. We still have 9 more episodes left in this season so there's still plenty of time for their music to appear. They probably don't want to overuse it either because it'd start to lose it's affect on the viewers.

The battle that I talked about above happened before the actual siege on Paris. They can still possibly base the events in Paris on what actually happened in history, so no worries.

Well, the battle may not have been the most exciting thing ever due to the stupidity of the commanders, but you can take comfort in knowing that that battle was actually based of a real battle. So it wasn't just the show writers being sloppy, they were going off history.