Simplenews category approval
Probably not possible out of the box.

You'll need to implement access for them, see for example https://www.drupal.org/node/1140606 for some discussions/ideas.

In 7.x-1.x, categories are terms, in 7.x-2.x they are separate entities.

However,I doubt that simplenews, in either 7.x-1.x or 7.x-2.x fully respects whatever access you define there, but patches to improve that are welcome.