Two considerations when installing a managed package in a sandbox are:
The installation link has to be modified to test.salesforce.com, because the default installation link points to login.salesforce.com which is for production orgs. To install a package in a sandbox org, the administrator has to replace login with test in the installation URL before clicking it.
The package will be removed any time the sandbox is refreshed, because refreshing a sandbox replaces its current data and metadata with those from its source org. If the source org does not have the package installed, then the sandbox will lose it after refresh. Any metadata changes to the package do not have to be recreated in production, because they are preserved during upgrades unless overwritten by the package developer. Install for Admins Only is not the only install option available; there are also Install for All Users and Install for Specific Profiles options. Reference: https://help.salesforce.com/s/articleView?id=sf.distribution_installing_packages.htm&type=5 https://help.salesforce.com/s/articleView?id=sf.data_sandbox_implementation_tips.htm&type=5

When an administrator deletes a custom field, Salesforce moves it to the deleted fields list for 15 days, during which time it can be undeleted or erased permanently. If the administrator undeletes the field within 15 days, most of its properties and data are restored, except for its field history data, which remains deleted and cannot be recovered. Reference: https://help.salesforce.com/s/articleView?id=sf.custom_field_delete.htm&type=5

Process Builder is a tool that can be used to implement this request. Process Builder can create record-triggered flows that execute actions when certain conditions are met. In this case, Process Builder can create a flow that executes when a contact with a title of CEO is created and updates the contact's account record with the CEO's name. Reference: https://help.salesforce.com/s/articleView?id=sf.process_overview.htm&type=5

A support process is a feature that allows administrators to define and enforce the stages that a case or work order must go through based on its record type. A support process determines which values are available for the status field for each record type. If a support process omits a certain value for the status field, such as Closed, then users will not be able to see or select that value when working with cases or work orders of that record type. Reference: https://help.salesforce.com/s/articleView?id=sf.customize_supporthome.htm&type=5

Process Builder is an automation tool that allows you to create processes that perform actions based on criteria that you specify. You can use Process Builder to update fields on related records when a record is created or updated. To meet the requirement of updating the parent object Referral when the Referral Date field is updated on the custom object Referral Source, you need to create a process that triggers when a Referral Source record is updated, checks if the Referral Date field has changed, and updates the Referral Date field on the related Referral record. Reference: https://help.salesforce.com/s/articleView?id=sf.process_overview.htm&type=5