1 - some common js/css files should be definitely included, then you can specify some other pages with their js and css files, which should work in offline mode, also you need to cache offline page URL with all it's css/js files.

2 - it's better to specify them as relative URLs, for example for `https://ci.una.io/test/dashboard` page you can specify it as `dashboard`, full URL is also fine.

3 - offline page is a page which is displayed for user when your site is offline, and the URL isn't included in 'URLs to cache on install' field.