All items in the request are validated using your data access except the enriched item, which is validated during the approval phase using the enricher's data access: This option is correct because when a request is pushed back to the submitter, the enriched item is preserved and validated using the enricher's data access during the approval phase. The rest of the items are validated using the submitter's data access when the request is submitted again.
Reference:
https://docs.oracle.com/en/cloud/saas/enterprise-data-management-cloud/edmra/approving-and-enriching-requests.html

The Owner permission is the highest level of permission that can be assigned to an application. Users with the Owner permission can perform various tasks such as: modify application registration, assign permissions for an application's data objects to other users and groups, manage an application's data objects such as properties, views, node types, node sets, hierarchy sets, etc., create and delete applications, and link dimensions across applications. Users with the Owner permission cannot import viewpoints from external applications, because viewpoints are created within Oracle Enterprise Data Management Cloud and are not imported from external applications. Users with the Owner permission cannot delete service administrators from an instance, because service administrators are created and managed in Oracle Cloud EPM through My Services by the Identity Domain Administrator. Reference: Working with Permissions - Oracle Help Center1; Registering Applications - Oracle Help Center2

When a data manager submits a request in a view that has subscriptions defined, the system generates subscription requests based on the subscriptions and assignees for each viewpoint. If multiple viewpoints have the same assignee, the system bundles the request items into a single subscription request for that assignee. Reference: Creating, Editing, and Validating Subscriptions - Oracle Help Center1

1. Use any approval method and do not select "Include Submitter": This option ensures that the submitter of the request cannot also be an approver of the request, which enforces the "four-eyes" principle that requires at least two different people to review and approve a request.
2. Use a serial approval method: This option does not guarantee that the submitter is not also an approver, unless the "Include Submitter" option is deselected.
3. Use any approval method with at least three different approval groups: This option does not guarantee that the submitter is not also an approver, unless the "Include Submitter" option is deselected.
4. Use a parallel approval method: This option does not guarantee that the submitter is not also an approver, unless the "Include Submitter" option is deselected.
Reference:
https://docs.oracle.com/en/cloud/saas/enterprise-data-management-cloud/edmra/creating-approval-policies.html

According to the reference, "A node type converter is a data object that enables you to share nodes between different node types in different applications." To keep account dimensions in sync between two applications, you need to create two node type converters, one for each direction of sharing. You cannot create a bi-directional node type converter, or specify a reverse conversion in requests.
To keep account dimensions in two different applications in sync and share nodes added to either application with the other, you can create two node type converters. One node type converter can have application 1 accounts as the source and application 2 accounts as the target, and the other node type converter can have application 2 accounts as the source and application 1 accounts as the target. This will ensure that nodes added to either application are shared with the other. (Reference: Oracle Enterprise Data Management Cloud 2022 Implementation Essentials, Module 3)