Hi Anty,
English Version
yes, the Plugin supports English-Versions. For Example try the following Link. The “WP AMP it up!”-Plugin reconize the language of Content and fill the AMP-Version into it:
https://www.amp-cloud.de/amp.php?s=https://developers.google.com/accounts/docs/AuthSub
Major SEO Plugins
The “WP AMP it up!”-Plugin should support all your other Plugins! Generally the AMP-Plugin take the whole source-code of a page and transform it to an AMP-HTML-Version. It’s just the html-tags would be transformated in amp-html-tags, and html-tags which were not supported in amp-html would be erased. So it could be, if a special SEO-Plugin use some not-supportet HTML-Tags, the AMP-Plugin dont support the whole SEO-Plugin.
Most it’s not a question of the Plugin, just a question of the source-code, because the AMP-Plugin just look at the source-code
Relation to other AMP-Plugins
No, there is no relation to any other AMP-Plugins. AMP-Cloud is an own service. AMP-Cloud.de exists since the beginning of 2016. At first it was a service withaout any “easy” plugin-possibilities and had to be integrated manually. To make it easier we launched a few weeks ago a own WordPress-Plugin which is just in relation with the service at itself.