Jus got into Dynasty warriors for the first time after getting into the whole Rot3K lore through Total War and got way too deep into it.

I'm currently downloading Origins after playing the demo. What exactly am I in for? Are there like a lot of equipment progression and stuff? How does faction allegiance work, if at all? Won't I have to pick a side at some point? Do I get to play with/along the heroes from the faction I ally with? Is there any deviation from the story? Do I get to change the course of events?

cheers