What does 'Range' do in the menu element?
The 'Range' in the menu list item element sets which list items at the current level the settings should apply to.
Acquia Cohesion renames to Site Studio from version 6.2. Tell me more.
Yes, you can build mega menus using Cohesion. Building mega menus requires advanced knowledge of jQuery in Acquia Cohesion and CSS.
Yes, the component link field supports both internal and external URLs.
No, the entity browser does not work for component defaults as the entities are content, not config.
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.