Tab interactions, button sets, layers and screen readers

HI. I want to use tab-style interactions (e.g., infographics with clickable segments/buttons that each reveal a different layer, all in a button set). The info in each layer will be audio narration and some text boxes. I want the user to be able to click any of the segments on the base layer at any time to move to another layer -  standard tab stuff, no need to close the layer, just click a different segment. 

I have 2 questions.

1) But how does this work with a screen reader? From what I can tell from other discussions, the only way to use layers in a user-friendly screen-reader accessible way (i.e. when on a layer, the focus order is of the layer only, not the whole slide) is to make the base layer not clickable and have "close" buttons on the layers- is this correct? 

2) How can I make the screen reader user know that a layer has popped up and so they now have to tab/up/down to find the new content? What are people doing for this?

Thanks so much

 Would be great if Articulate could provide some articles about suggestions or best practices  on how to build these more complex interactions with screen readers in mind - I have read all there is about accessibility on Articulate and they offer a very light touch but nothing in depth about layers, tabs, audios narrations, quizzes etc.