1 - We do not. We do provide automated conversion to AMP of the Mailchimp standard plugin. You would need to do a bit of custom coding to AMPlify the AWeber form. How do you currently integrate aWeber with your site? a plugin?
What we do, we AMPlify all the catagories, products, search, etc pages. We also provide a "mini-cart" that's updated live on AMP pages. Then when user clicks on "Check out", they are sent to the standard HTML checkout page that already exists on your site.
Have you checked our WooCommerce demo site
? it's a standard install of current WooCommerce with no customization except for colors.
Please have a look at this page which is a variable product
3 - Those which create content where users can benefit from the speed of AMP on mobile devices. On a commerce site, you want them to browse your categories, or search, and view your product pages all AMP. Then regular articles, blogs, etc are a given.