Explanation
The data streams that use the Marketing Cloud Connector refresh data using Marketing Cloud's Automation Studio. The Marketing Cloud Connector is a feature that allows you to stream data from Marketing Cloud to Data Cloud in near real time. The connector uses Automation Studio to schedule and run data extracts from Marketing Cloud data extensions and send them to Data Cloud via SFTP. You can configure the frequency and time of the data extracts in Automation Studio. References: Marketing Cloud Connector

These two phases are distinct phases of data model management in Data Cloud. Data ingestion is the process of bringing data from different sources into Data Cloud using connectors or APIs. Data modeling is the process of mapping the ingested data to the Data Cloud canonical model or creating custom data model objects. Reference: https://help.salesforce.com/s/articleView?id=sf.c360_a_data_cloud_data_model.htm&type=5

Explanation
This method should be used when performing aggregations in windows of 15 minutes on data collected via the Interactions SDK and Mobile SDK. Streaming Insight allows you to query and aggregate data from real-time streams using window functions.
References:https://help.salesforce.com/s/articleView?id=sf.c360_a_streaming_insights.htm&type=5

These three features can be used to validate the data in the unified profile object. Data Explorer allows you to view the ingested data from different sources and how it is mapped to the unified profile object. Query API allows you to query the unified profile object using SOQL or SQL queries. Profile Explorer allows you to view the unified profile records and their attributes. Reference: https://help.salesforce.com/s/articleView?id=sf.c360_a_data_explorer.htm&type=5 https://help.salesforce.com/s/articleView?id=sf.c360_a_query_api.htm&type=5 https://help.salesforce.com/s/articleView?id=sf.c360_a_profile_explorer.htm&type=5

These are the two dependencies that need to be removed prior to disconnecting a data source. A data stream is a process that ingests data from a data source into Data Cloud. A segment is a group of customers that meet certain criteria based on their data. If a data source is disconnected, any data streams or segments that depend on it will no longer function properly. Reference: [Data Sources], [Data Streams], [Segments]