I'm having trouble finding any info about the locations of public guild stores. Someone in my guild said i needed to find a guild trader but i can't even locate that. I'm in the Altmeri Domonion zones.
Look at your in-town maps. They added two new icons, one for the dye station (looks like a paint pot) and one for the guild traders (looks like a guild tabard with crossed swords scales inside, sort of heraldic). If that doesn't help, I'm sure someone will post a screenshot for you.
None inside that I've seen. There are some in some pretty out-of-the-way places, places you might not expect them to get much business, but I suppose that just means that the more desirable ones will auction off for more. But inside? Haven't seen one yet.