What capability should an Integration Architect consider if there is a need to synchronize data changed in Salesforce to a 3rd party with a JSON-based API endpoint?

Northern Trail Outfitters (NTO) is looking to integrate three external systems that run nightly data enrichment processes in Salesforce. NTO has both of the following security and strict auditing requirements:
1. The external systems must follow the principle of least privilege, and
2. The activities of the eternal systems must be available for audit.
What should an Integration Architect recommend as a solution for these integrations?

Northern Trail Outfitters submits orders to the manufacturing system web-service. Recently, the system has experienced outages that keep service unavailable for several days.
What solution should an architect recommend to handle errors during these types of service outages?

business requires automating the check and update of the phone number type classification (mobile vs. landline) for all in-coming calls delivered to their phone sales agents. The following conditions exist:
1. At peak, their call center can receive up to 100,000 calls per day.
2. The phone number type classification is a service provided by an external service API.
3. Business is flexible with timing and frequency to check and update the records (throughout the night or every 6-12 hours is sufficient).
A Remote-Call-In pattern and/or Batch Synchronization (Replication via ETL: System -> Salesforce) are determined to work with a middleware hosted on custom premise.
In order to implement these patterns and mechanisms, which component should an integration architect recommend?

Universal containers is migrating to Salesforce from a legacy system with existing SMTP-based integrations.
What Salesforce platform capability should an Integration Architect consider?