ohh ok so there is two difficulties? Sorry i have just started reading about the later stages of the game, thats why i'm making inquiries as how it will work :P so far i have only watched a couple of live streams but that was during the early zones when beta was first released. I'm just the kind of person that needs to be well informed before i go buy a game and i thought asking here, I would find people that knew the most about it.
Yes, for every dungeon there are 4 different paths. One path is called "Story mode" and is intended to primarily let you experience the lore behind the dungeon and get familiar with boss and environment mechanics. The other 3 modes are called "Explorable modes" and are only unlocked when you've finished the Story mode. Explorable modes are different paths with different bosses in that same dungeon, they're difficult and require planning.
As for end-game events, no they're not open to low-level characters. Side-kicking only works downwards so people can go back to places they've already visited without feeling overpowered, it doesn't work upwards so people can't just skip content and go for the final boss in day 1. Now, like dungeons, events also have 2 difficulty levels : normal and elite. Normal events are what you'll be doing most of the time, but now and then there will be a huge boss fight that requires coordination and team play, that would be an elite event.
The important thing to keep in mind is that whether it is a dungeon or an event, your level and you gear will never trivialize the content. Difficulty will be what it will be and your skill will decide if you get to pass.
I will be leveling to 80 as fast as possible. Why not? At level 80 I will have full access to all content that the game has to offer, thanks to down scaling. Would rather have the option of doing anything in any area of the game.