For monitoring customer status and making decisions within a journey in Salesforce Marketing Cloud, the entrysource's data extension must have a primary key and a subscriber key. These keys ensure that the data is properly linked to the contact, allowing the journey to reference and update status data accurately as the contact flows through the journey.
Reference:Salesforce Marketing Cloud Documentation on Data Extensions and Keys

Reference:Salesforce Documentation - Journey Builder Goals

To honor the opt-in communication method of subscribers inJourney Builder, Northern Trail Outfitters (NTO) should create one Entry Source for each messaging channel (email and SMS). This ensures that the journey can differentiate and respect the preferred communication method of each subscriber based on how theyopted- in. Each entry source can then be used to trigger the appropriate welcome series content for the respective channel. Reference:Salesforce Marketing Cloud Documentation

To ensure that a daily report of sends across all business units is sent to the director each day, the marketing developer should schedule the report in Marketing Cloud and configure it to email the filedirectly to the director. This can be done by setting up a report in Email Studio, defining the parameters and schedule for the report, and specifying the recipient email address. This ensures that the director receives the necessary data in a timely manner without manual intervention.
Reference:
Salesforce Marketing Cloud Documentation: Schedule Reports

Reference: Salesforce Marketing Cloud Documentation on Content Management and Metadata Tagging