Most are outside. We love this part of the holidays at Epcot and try to get to all of them during our stay. Every country has something, even if just a New Year tradition or a major holiday if they don't celebrate Christmas. Though the locations might change and the "stand" might be updated, we look for a white or off white stand with a scroll or flat surface on it. Part of the holiday story is printed here if you want to read it. This is the area where the storyteller will appear, so we try to get there a few minutes before. People just gather around to hear the story.
I think the only pavilion that has one inside is the USA, they do Kwanza outside and Hanukkah inside. Mr & Mrs Clause are outside too but are taking requests from kids (of all ages) and not telling their story.
The appearance times are printed on the park Times Guide, hard to see all of them in one day due the appearance times being staggered, and they don't appear at night. It's well worth making time to see them.