Under Administration -> Configuration -> System Settings you will find a few more system-wide settings.
In the dropdown Project Creation, you can specify who can create new projects in your instance. You have a choice between system admins and all other users.
You need a token every time you want to login into your private registry from Docker.
You can specify how many minutes it is valid.
As described here.
As explained here.
If you enable this feature, all users will only be able to pull images. Independent of their permissions, none will be able to push images, tag images, and delete repositories.
As explained here.
As a system admin, you must enable webhooks so that project admins can add webhooks to their projects.