The consolidation rate is the amount by which source profiles are combined to produce unified profiles, calculated as 1 - (number of unified individuals / number of source individuals). For example, if you ingest
100 source records and create 80 unified profiles, your consolidation rate is 20%. To increase the consolidation rate, you need to increase the number of matches between source profiles, which can be done by adding more match rules. Match rules define the criteria for matching source profiles based on their attributes.
By increasing the number of match rules, you can increase the chances of finding matches between source profiles and thus increase the consolidation rate. On the other hand, changing reconciliation rules, including additional attributes, or reducing the number of match rules can decrease the consolidation rate, as they can either reduce the number of matches or increase the number of unified profiles. References: Identity Resolution Calculated Insight: Consolidation Rates for Unified Profiles, Identity Resolution Ruleset Processing Results, Configure Identity Resolution Rulesets

You can add new measures or dimensions to a Calculated Insight by selecting them from the available attributes list

This platform is going to present a challenge in terms of connection limits for Data Cloud. Data Cloud supports up to 3 Marketing Cloud connections per org, which means that only 3 Marketing Cloud accounts can be connected as data sources or activation targets. The other platforms have higher or no limits for connections. References:
https://help.salesforce.com/s/articleView?id=sf.c360_a_data_cloud_limits.htm&type=5

The Email field from a CRM Contact object should be mapped to the Contact Point Email entity in the Customer 360data model. This entity represents an email address that is associated with an individual or an account contact. References: [Contact Point Email Entity]

The Data Cloud User permission set is the minimum permission set needed to accommodate this use case.
The Data Cloud User permission set grants access to the Data Explorer feature, which allows the user to review individual rows of ingested data and validate that it has been modeled successfully to its linked data model object. The user can also make changes to the data model object fields, such as adding or removing fields, changing field types, or creating formula fields. The Data Cloud User permission set does not grant access to other Data Cloud features or tasks, such as creating data streams, creating segments, creating activations, or managing users. The other permission sets are either too restrictive or too permissive for this use case. The Data Cloud for Marketing Specialist permission set only grants access to the segmentation and activation features, but not to the Data Explorer feature. The Data Cloud Admin permission set grants access to all Data Cloud features and tasks, including the Data Explorer feature, but it is more than what the user needs. The Data Cloud for Marketing Data Aware Specialist permission set grants access to the Data Explorer feature, but also to the segmentation and activation features, which are not required for this use case. References: Data Cloud Standard Permission Sets, Data Explorer, Set Up Data Cloud Unit