What Salesforce technology should an Integration Architect consider when needing to securely expose an external system User Interface from within the Salesforce UI and provide that system with information about the user?

What is the first thing an Integration Architect should validate if a callout from a Lightning Web Component to an external endpoint is failing?

Northern Trail Outfitters (NTO) uses Salesforce to track leads, opportunities and order details that convert leads to customers. However, Orders are managed by an external (remote) system. Sales representatives want to view and update real-time order information in Salesforce. NTO wants the data to only persist in the external system.
Which type of Integration should an architect recommend to meet this business requirement?

Universal Containers is hearing complaints from users that recently released changes arebreaking existing functionality.
What type of testing program should a Technical Architect implement to reduce or eliminate this complaint?

Universal learning (UC) is embarked on Salesforce transformation journey, UC will decommission the legacy CRM system and migrate data to Salesforce. The data migration team asked for a recommendation to optimize the performance of the dataload to Salesforce.
Which approach should used to meet the requirement?