/wp-content/plugins/ directoryA: You do not need it! Your visitors need it ;-) The most performant way to deliver a website is static html content. But this is not the best way for all single posts of your blog because you are losing the benefit of dynamic elements like captcha checks. So the optimal solution would be only make the landing pages / the start page static.
A: Yes. A CDN will cache the content of you blog posts. Usually the CDN ask for changes on your server before deliver the cached content. So real static content can speed up this process to.
A: This plugin use the permalink provided by your WP core installation to create and check if a static version of the post/page is still stored on your webserver. So if do you change the definition of the permalink structure the plugin will not find prior stored content. We are thinking about a log for all static URLs. But this will need additional storage in the database and we want try to have as small/performant footprint as possible. Perhaps we will change this with a future version. But it is not on our agenda at this time.
A: If your server support http and https please make sure to create the static files while WP has configured the WP address and website address to the httpS:// version. BTW: Of course your server must support https connections to URI of your blog. = Q: Can I make a static version of my whole WP blog to transfer it on an punblishing server? = A: No. There are other plugins to do this job. But this plugin was developed with the aim to keep as most dynamic features of Wordpress and plugins as possible.
Features marked as "experimental" in the admin menu are experimental! This means: We think it is a good extension to our plugin that we would like to include in a future version, but we are not sure yet about the best solution that works for all or most people. So please feel free to use and test it and report back to us about it. Experimental features might be removed in an update, if it does not work out. So please pay close attention to our changelog!
These are bugs or unexpected glitches that we know of, but that do not have an impact on the majority of users, are not security relevant and will perhaps be fixed in the future - if we have time to spend or you provide us with a lot of "Kölsch" ;-)