Dark Raiden's story is quite complex. He started as Raiden, the protector of Earthrealm. However, after seeing so much violence and the constant threat to Earthrealm, he became darker. He decided to take more extreme measures to protect his realm. He was tired of the rules that seemed to be constantly exploited by the enemies. This led him to make some very controversial decisions, which put him at odds with some of his former allies.
One key event is his decision to break away from the traditional code of conduct. Another is his more aggressive stance against enemies, like his battles with certain Outworld forces. Also, his interactions with other Kombatants changed significantly. For example, his relationship with Liu Kang became more strained as he took on this darker role.
Well, the canon status of MK comics isn't straightforward. It might be canon within certain story arcs or universes, but not across the board. Different interpretations and continuities can come into play.
Well, without reading it specifically, it could be about Naruto in a scenario where he becomes the champion in a context related to Raiden. Maybe it involves Naruto facing challenges in a Raiden - inspired world or having to prove himself worthy of some sort of Raiden - related title. It could also potentially involve Naruto using powers or abilities associated with Raiden.
The length of the Raiden Shogun story quest can be quite subjective. On average, it might take around 3 to 5 hours. However, if you take your time to enjoy the cutscenes and dialogue fully, it could extend longer.