Here is how to calculate average session duration and average time on page. Also learn the difference between them in google analytics.
Google analytics allows you add multiple views to the same property. This way you can create multiple filtered view. Here is how to do it.
Learn about google analytics trash can and how to restore any property or view from it. It is similar to the trash can located on your mac desktop.
Here is how to use a built-in listener in google tag manager to track multiple buttons and clicks on a specific page.