Customization and scaling

I’ve deployed on AWS, can I attach to the EKS and then to the hub a EFS and allocate parts of it to the users? Will it be shared memory? (I found this but it was unclear to me how stable it is and what’s better practices, have a big instance storage or the dynamic storage).

Also, what happens if I change the cluster instance type? Is the data lost (user/hub)? Same goes for the scaling node group I configured, is the storage stateful?