Distributing Frontend Assets with Plugins

1 – it’s up to you and subject to opinion, so not best suited to WPSE.

2 – Never hardcode paths. WP has whole range of functions for finding file paths and URLS. plugins_url() will get you the full URL to the plugins directory, handling whether you are using http or https and canonicalising the domain name for you. It will take parameters for a file relative to your plugin’s directory by using PHP’s magic __FILE__ constant too: plugins_url( 'images/plugin_icon.png', __FILE__ ) for example.

Similarly, plugin_dir_path( __FILE__ ) within a plugin file will get the full system file path to the file.