changing the VNN is fairly easy, just edit the VNN resource in failover cluster manager. Once renamed take the resource offline which will take the instance offline too. Restart the sql server agent cluster resource which will bring online the VNN and the clustered sql server service. Check that the new VNN is recognised by the SQL Server instance.

To rename the nodes i would uninstall all clustered applications and then remove the node from the cluster. Rename the node and reintroduce into the cluster, then re install clustered apps.