Explanation
These three out-of-the-box connectors are available for Data Cloud. They allow you to ingest data from Marketing Cloud, B2C Commerce, or Amazon S3 into Data Cloud and map it to the Data Cloud data model.
References:https://help.salesforce.com/s/articleView?id=sf.c360_a_connectors.htm&type=5

A Data Model Object (DMO) that inherits the name, shape, and semantics of the reference object is called a Standard DMO. A reference object is a predefined object in the Data Cloud data model that represents a common entity or concept, such as Individual, Order, or Product. A Standard DMO is a copy of a reference object that you can use to ingest data from a specific source without modifying the original reference object. A Standard DMO has the same fields and relationships as the reference object, but you can add custom fields or relationships to it if needed. Reference: Data Model Objects

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. Reference: https://help.salesforce.com/s/articleView?id=sf.c360_a_streaming_insights.htm&type=5

Explanation
This configuration will ensure that Data Cloud only ingests new files from the Amazon S3 bucket and updates or inserts new records into the data stream without deleting existing records.
References:https://help.salesforce.com/s/articleView?id=sf.c360_a_data_cloud_amazon_s3.htm&type=5

Explanation
Numeric is the only type of measures that support aggregate functions. Measures are numeric fields that can be aggregated using functions such as SUM, AVG, MIN, MAX, or COUNT. For example, you can use a measure to calculate the total revenue or the average order value from your data. Date, Text, and Boolean are not types of measures, but types of dimensions. Dimensions are fields that can be used to group or filter data, but not to perform calculations. References: Measures and Dimensions