Reference: Salesforce Premier Support

Reference: Salesforce Documentation on Field-Level Security

For In-App Messaging, the recommended standard field options to include are First Name, Last Name, Email, and Account Number. These fields ensure that customer service agents have the essential information needed to identify and authenticate the customer, facilitating a more personalized and efficient service interaction. The Account Number is particularly crucial as it provides a direct link to the customer's specific details and transaction history within the company's systems.

The seamless transition from bot interactions to live agents in complex inquiries can be facilitated through multiple features:A. Escalation Rules automatically transfer chat sessions to agents based on predefined criteria, ensuring timely intervention.B. Contextual handoff functionality retains chat history and customer data, equipping the agent with the context needed to provide effective support immediately.C. Supervisor Console allows for manual oversight and direct chat session transfers to specific agents, enhancing control over quality and distribution of tasks.These combined features ensure a comprehensive approach to managing bot-to-agent transitions, maintaining continuity and customer satisfaction.
References: https://help.salesforce.com/articleView?id=service_presence_configuring.htm

When migrating historical call recordings, secure and scalable storage options are crucial. External cloud storage solutions, integrated with Salesforce, provide the best option for handling large volumes of data such as call recordings. These solutions offer scalability, security, and easy accessibility, which are necessary for effective data management within Salesforce environments. Thus, "B. External cloud storage with Salesforce integration" is the most suitable storage option for this purpose.
Reference: Salesforce Files and Content Management