Do I have to use IMCE?
No. Acquia Cohesion allows the site builder to select, either use of IMCE or Entity browser for browsing and selecting images.
Acquia Cohesion renames to Site Studio from version 6.2. Tell me more.
The 'Range' in the menu list item element sets which list items at the current level the settings should apply to.
Running the composer update command will update any composer packages that have newer versions available.
Google maps may not be showing if you have not set a Google maps API key.
The Youtube video embed is responsive so it should expand to the width of its parent. If you do need to set a width you can apply the Width CSS property through the Style Builder.