Manage Docker image volumes

Command below brings list of volumes on my machine.

docker volume ls

How to know which volume belongs to which image and which one belongs to nothing and can be safely removed?

I would like to transfer my system that consists of Docker images and volumes transfer to another pc. I can save images by executing command:

docker image save my_image -o my_image_archive.tar

But how to transfer volumes with data to another pc in order to make transferred images to use volumes with original data?