A validation rule on the Opportunity Product object to require custom date fields based on the product family will ensure that the data is captured properly. A validation rule can check if the product family matches the service plan and if so, require the start and end date fields to be filled out. This way, AW Computing can capture the term length for each service plan sold. References: https://help.salesforce.com/s/articleView?id=sf.
fields_about_validation_rules.htm&type=5

A primary account relationship is a feature that allows you to link a contact to a single account as its primary account. A primary account relationship is required on a contact regardless of the page layout settings or the contact to multiple accounts feature. This means that you cannot remove the primary account from a contact, but you can change it to another account. You can also add secondary accounts to a contact if you have enabled the contact to multiple accounts feature. References: https://help.salesforce.com/s/articleView?id=sf.
contacts_multiple_accounts.htm&type=5 https://help.salesforce.com/s/articleView?id=sf.contacts_fields.
htm&type=5

REGEX is a function that allows administrators to check whether a text value matches a regular expression pattern. Regular expressions are a way to define complex patterns of characters using symbols and operators.
REGEX can be used to enforce consistent formatting for a field value by specifying the required length, characters, and separators.

Flows are tools that automate business processes by collecting data and performing actions in your org or an external system. Flows can be triggered by various events such as record creation, updates, or invocations from other processes or flows. Flows can also send email alerts as part of their actions. To send a notification when a record is deleted and by whom, and to maintain their own discovery information, an administrator can use a flow that runs when a record is deleted, queries the record owner's email address and discovery information from another object or variable, and sends an email alert with those details. References:
https://help.salesforce.com/s/articleView?id=sf.flow_concepts.htm&type=5

Case Source updates to 'email' before the record is saved because the Process Builder runs before the auto- response rule. Then, an email is sent out using Template2 because the auto-response rule evaluates the Case Source value after it is updated by the Process Builder and matches the criteria for Template2