There's an existing wordpress plugin that creates AMP formats automatically by adding /amp onto the end of any posts URL. I'm worried about duplicating my content at multiple URLs and wondering if adding some parameter like ?v=amp would be better? Also, if a parameter is used to render the page via AMP, how do we let Google know about these pages? Can we submit a separate AMP sitemap?
The AMP standard uses a Canonical link to define the original source and a link rel=amphtml on the canonical page to point to the amp version. Google understands both so no action is needed on your part if you amp pages pass validation.