so how does this multiclassing thing work?

[Eiralys]

so can I be all classes on one character?

and if so is there a point to having more than one char?

You can but it takes a lot of work. I have different characters on different worlds mostly because of all the login problems. But I also want to see how the story progresses differently in each city. So, depending on what you like, you can have just one "jack-of-all-trades" or you can have a few characters and watch the story unfold from all points of origin.

[HEC]

But I also want to see how the story progresses differently in each city.

The story differs a little realy between the cities, almost not at all actually unless indeed you count the little go-and-fetch side quests as "story" so that would be the last reason to have multiply characters I'd say.