Why is it important to select the right root object when you use the dataset builder?

A company uses role hierarchy to implement data security in Salesforce. They want the same role-hierarchy-based security model to apply in Einstein Analytics, but want the users in a role to see data owned by other users in the same role.
Using the "flatten" transformation, which attribute setting achieves this requirement?

Einstein Discovery gives you several different kinds of recommended insights. Which of these insights is descriptive?

Max of objects that can be enabled for Data Sync

A Einstein Analytics consultant is asked to help a company report on their sales activity. The company wants to train some users to create their own dashboards. They also want another team to only be able to use the dashboards.
What must be configured to address these requirements?