Explanation
To meet the requirements of sharing special deposit products for employees, the administrator should create a Financial Account sharing rule based on criteria. A Financial Account sharing rule is a sharing rule that grants access to financial account records based on record owner or field values. A sharing rule based on criteria is a type of sharing rule that grants access to records that meet certain criteria. By creating a Financial Account sharing rule based on criteria, the administrator can share the special deposit products with the customer service employees within a specific group based on a field value that indicates the product type.

Rollup By Lookup (RBL) is a feature in Financial Services Cloud that allows you to display summary calculations of financial account information, such as balances, market values, and cost bases. You can use RBL to roll up financial data to all joint owners' primary households by doing the following:
Create custom RBL rules to rollup the joint owner balances using the Joint Owner field on the Financial Account object.
Enable RBL rules that rollup balances using Financial Account Role for joint owners using the Account Role field on the Account Contact Relationship object. Verified References: : Salesforce Financial Services Cloud Implementation Guide, page 75.

Explanation
Feed tracking has to be enabled for the Action Plan object in order to add a Chatter component to the Action Plan Lightning record page. Feed tracking allows you to see updates on records in Chatter feeds. You can enable feed tracking for custom objects, such as Action Plan, from the setup menu. Once feed tracking is enabled, you can add Chatter components, such as Feed or Publisher, to the record page using the Lightning App Builder. References: [Feed Tracking], [Chatter Components]