Usually there aren't too many responses to questions about creating accessible files because it's a fairly specialized area. I only know about it in a superficial way.
Chad Chelius has created a Lynda.com video which has the best information I've seen about the subject:
You can watch Lynda.com for a week at this link:
Hi. I know it's old, but I found the CS5 Indesign video on Adobe TV to be a big help. I had to tag and structure and then add the elements to the Articles.
This video shows which tags in InDesign are compatible with Acrobat.
Using InDesign CS5, I was able to make my newsletter entirely 508 compliant without any further editing in Acrobat Pro. Not as lucky with InDesign CC tho :-/.
Still, the information on the tags and locating the structure panel to adjust the read order hierarchy is still good.