Why aren't my base styles updating in the preview?
If you're removing styling from a base style, those styles still apply until you have saved the base style.
Acquia Cohesion renames to Site Studio from version 6.2. Tell me more.
Base styles are CSS styles for HTML elements.
Yes. You should revision your Acquia Cohesion assets like other configuration using a service like Git.
HTML is escaped when using Drupal tokens in Site studio as a security measure, this follows Drupal core.
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.