Explanation
To track all cases that reference the new product and give read/write access to the product's two lead engineers, the administrator should create a queue and a criteria-based sharing rule. The queue will allow assigning cases that meet certain criteria, such as having a specific value in the Product field, to a group of users. The criteria-based sharing rule will grant read/write access to the queue members for cases that match the same criteria. References: https://help.salesforce.com/s/articleView?id=sf.queues_overview.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.sharing_criteria.htm&type=5

Explanation
Page layout and field level security are two factors that determine whether a user can see a new field on a record. To troubleshoot this issue, the administrator should ensure that the page layout for the user's profile has been updated to include the new field and that the field level security of the field for the user profile allows read or edit access. References:
https://help.salesforce.com/s/articleView?id=sf.customize_layoutoverview.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.admin_fls.htm&type=5

Explanation
To test the impact of a critical update before it is auto-activated, you should activate it in a sandbox first. This way, you can verify that your customizations and integrations work as expected without affecting your production org.
References: https://help.salesforce.com/s/articleView?id=sf.admin_critical_updates.htm&type=5