Is there a complete library of DCAD details for ADA compliance? Beyond the ones included in the symbol library. I have seen them in ACAD, but cannot import without major headaches.
What issues are you having in importing from Acad? What specific details are you looking for - site, path-of-travel, toilet rooms, ...? You will also find that even with what you may get there will be a certain amount of modifications to bring them into current compliance with both the ADA and your state requirements.
I think you'll need to beg and borrow from Dcad'rs who've already translated what they've needed from DWG or DXF into AEC. Also check out CheapTricksWare for what has already been done (see here for the main index page).