I think the best explanation of the 10 year story came from one of the early Q&A sessions:
We break this story up, as we choose the title “Chronicles of Elyria” as opposed to “World of Elyria” or “Elyria Online” or any other name, because the concept of “Chronicles” to us speak to us of texts, of books, of epic novels and that is what we wanted to recreate with this game, this idea of you living out this epic story.
So we have divided up this 10-year story into books, and each book is going to last about a year, there is about 10-books in this story, these books are further divided up into chapters and the chapter for us could be months. What happens is that at the transition point, at the inflection from one chapter to another, we don’t know what the players are going to do, how they’re going to come out of that chapter. At any one time, the engine is always looking at how close you are to one of the possible outcomes and it is trying to drive you to one of those outcomes. It is introducing quests, creating conflict and introducing NPCs that have certain personalities so they grow up and have conflict.
The choices that the players make might steer them towards one of the others, as soon as they do, it adds weight and credibility to it and drive them to that other step. This whole story is built around this concept of triggers and things that players can do, and it might be that they can start heading in a direction that we didn’t anticipate at all and it has something to do that is cataclysmic or awesome or whatever. But we don’t have the whole story upfront, we have a plan for an overall and we do have writers on staff and as things progress we have the opportunity to respond to things as necessary. This isn’t something players need to look for it is something they will be involved in whether they wanted to be or not.
The thing to remember is that this story is for the world, some parts might be local, some parts impacting everywhere all at once. There is no 'right' place to be in order to take part.
It is really important to note that the 10 year story is just one of the layers of the story of Elyria. You have the 10 year story, you have the dance of dynasties, you have personal stories based on your birth date, stories based on the ecosystems around you. Some of those are almost completely player driven, such as the dance of dynasties, some are driven by the Soulborn Engine, such as your personal destiny. There is a bit more about the layers of story in this article which is not direct quotes but a summary of information shared by the developers at the time.
As for story points they are not directly for participating in the 10-year story. The idea of story points is any play that goes towards you gaining skills or you completely achievements earns you points, this is covered in the Developer Journal on Bolstering and Earn to Play. It is simply being active in the world, and all activity helps drive forward the world story on one of the many layers.