A window function is aunique requirement of a Streaming Insight query. It defines the time interval for the query to run on the streaming data and the frequency of the query execution.
References:https://help.salesforce.com/s/articleView?id=sf.c360_a_streaming_insights.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 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 mappingthe ingested data to the Data Cloud canonical model or creating custom data model objects. References:https://help.salesforce.com/s/articleView?id=sf.c360_a_data_cloud_data_model.
htm&type=5

These two features are impacted by the timezone setting in the org Data Cloud is provisioned in. The segment schedule determines how often a segment is refreshed based on the selected timezone. The activation schedule determines how often a segment is exported to an activation target based on the selected timezone. References:
https://help.salesforce.com/s/articleView?id=sf.c360_a_segmentation_schedule.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.c360_a_activation_schedule.htm&type=5

Data Cloud can address these two common use cases by providing a platform that allows customers to ingest, map, enrich, and activate data from various sources using the Customer 360 data model, and by enabling customers to create segments, insights, and activations based on their customer data. Reference: [Data Cloud Overview], [Customer 360 Data Model], [Data Activation]