Acquia Cohesion renames to Site Studio from version 6.2. Tell me more.
No, you cannot use SCSS variables in your codebase inside the Acquia Cohesion interface.
To use an SCSS variable, enter your chosen variable into the appropriate CSS property.
No, the entity browser does not work for component defaults as the entities are content, not config.
Cohesion layout revisions are created at the same time as node revisions, but not always deleted at the same time.
Use the "Node Revision Delete" contributed module to manage your node and associated Cohesion layout revisions.
Use the tools included in the "Entity Reference Revisions" contributed module.
Opacity is set using a decimal where 0 is transparent, 0.5 is 50% and 1 is solid.