Change Sets and Data Loader are deploy solutions that should be used to ensure skills-based routing is operational in Production. Change Sets are collections of metadata components that can be deployed from one Salesforce org to another. Change Sets can be used to deploy the configuration settings for skills-based routing, such as the skills, skill assignments, routing configurations, presence configurations, or service channels. Data Loader is a tool that can be used to insert, update, delete, or export records in Salesforce. Data Loader can be used to deploy the data records for skills-based routing, such as the work items, agents, queues, or routing priorities. Verified References: Service Cloud Consultant Certification Guide & Tips, Change Sets Overview, Data Loader Overview

Setting up a sharing set to grant access based on the community member's contact record is a solution that can implement the requirement of enabling community members to access, create, and manage cases online. A sharing set is a feature that allows administrators to grant access to records for community users based on their user profile and a common field on the user and parent records, such as the contact or account fields. A sharing set can help ensure that community members can only see and edit their own cases or cases related to their contact or account. Verified References: : https://help.salesforce.com/s/articleView?id=sf.
networks_sharing_set.htm&type=5 : https://help.salesforce.com/s/articleView?id=sf.
networks_sharing_set_create.htm&type=5