Word press Plugin UI conflict with other themes css

I need two clarification from the word press plugin developer.

1. If we are developing any new plugin using that is not going to be
   usage of word press admin user , it will create 2 new pages in the
   front end side (in website) using short code
   (https://developer.wordpress.org/reference/functions/add_shortcode/)
   it will render styles , script and template. In website user may use
   different themes, Those theme CSS are affecting the pages created by
   plugin and plugin UI. Is there any solution for this.

2. Apart from word press plugin marketplace is there any other way we
   can publish the plugin.