1. Salesforce Connect allows connecting Salesforce to external data sources using OData. It supports OData 2.0 and 4.0 protocols to connect to systems like SAP and Microsoft. 2. Data can be accessed from external systems through Salesforce using the Force.com REST API and exposed via OData. Apex can also be used to build OData services to access external data. 3. Examples of using Salesforce Connect with Heroku Postgres database were shown to demonstrate retrieving and updating data between the two systems via OData endpoints.