It's all done in way to be as unobtrusive as possible, mostly by hiding admin pages and settings and redirecting pages on both the front-end and admin side.
The plugin also supports custom post types and custom taxonomies..
Front Page Displays is not set to show on page, then this plugin will update it to that option, but you still need to select page to act as the front page.
Not doing so will mean that your post page can still be visible on the front-end of the site..
If you're looking to disable them completely, check out Disable Comments plugin ..
If you are using custom post type that supports the category and or post tag taxonomies, they will be visible and accessible for the custom post type..
If you don't want your posts, comments, categories, or tags, delete them prior to activation.
The exception to the database modifications is related to the way your site displays it's front page, as mentioned above..
You can visit the support forums or the issue section of GitHub repository..
View the plugin on GitHub to see list of this plugin's and To-Do list of items yet to be included, as well as log any issues ..
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