Hi there,
1. For all of the content to display, you would need to have Beaver Builder pro.
You can use Beaver Builder free as well but the pro content will be missing.
2. Yes – most of the options are in the customizer so you don’t need to reinstall GB.
Gutenberg editor is now the default WordPress editor so you don’t need the plugin either.
3. Yes – the site library templates are completely customizable so you can add/remove any content as you wish.
Let me know if this helps π