Acquia Cohesion renames to Site Studio from version 6.2. Tell me more.
You can create more than one template to provide layout and style alternatives with the use of the template selector.
Yes, you can build mega menus using Cohesion. Building mega menus requires advanced knowledge of jQuery in Acquia Cohesion and CSS.
You don't. You apply a Descendant selector. These use a (Space).