To ensure the changes make it accurately to production, the administrator should create a change set, upload it to production, and deploy the change set. A change set is a collection of metadata components that can be moved from one org to another. The administrator can use change sets to migrate point-and-click changes, such as custom objects, fields, layouts, and settings, from the sandbox to the production org. The administrator can create a change set in the sandbox, add the components that have been changed, upload it to the production org, and deploy it in the production org.

This option allows the Salesforce Admin to create a customer user from an existing contact that is associated with a customer account. The customer user inherits the role, profile, and permission sets from the contact. The Salesforce Admin can also specify a username, email address, and nickname for the customer user.

To limit the fields available in the customer portal, the administrator should use Field-Level Security to remove access to the unwanted fields. Field-Level Security is a feature that allows the administrator to control the visibility and editability of fields for different profiles and permission sets. The administrator can use Field-Level Security to hide or make read-only the technical codes and internal information fields for the customer portal profile or permission set.

This permission allows the manager to create, edit, and delete all users in the org, including internal users. This permission overrides the sharing settings and role hierarchy that normally restrict access to user records. To limit the manager's access to only community users, the manager should be given the Manage External Users permission instead2

When selecting a template for your sites and portals, you need to keep in mind some points, such as:
Insurance Agent Portal template becomes available once Financial Services Cloud is correctly set up in an org. This template is designed for insurance agents who need to manage their leads, opportunities, policies, claims, and referrals.
Industry-specific templates as well as Lightning Bolt solutions are available today. Templates are preconfigured site designs that include pages, components, and settings. Lightning Bolt solutions are industry-specific solutions that include templates, themes, flows, apps, and components.