Guild Wars 2

I was wondering if anyone had information (more than what meager amount is in the tooltip/description of it) as to where these merchants can be found.

Are they in towns only or am I going to need to search with someone that has maps completed? If no… is Orr part of central Tyria? Is DT or SW part of core Tyria?

Is there an icon on the map that denotes these merchants or are we going to have to basically play hide-and-seek through all these MASSIVE area’s of land to find them?

Do they move once a day or once a week? I seem to recall the video say they change location each week but still want to be sure… in case it changed.