Yes, additional locations can be added. I just put this together quickly and haven't added all sites yet.

Yes, I can add collaborators to the map so they can edit it. You will need a Gmail account so that I can add you. Once added, you will have the option to edit it. There is an option to allow ANYBODY to edit it, but I wanted to keep it as accurate as possible. Opening it to anybody on the Internet would cause some issues.

It is already saved and will never go away, unless Google goes away. Google Maps allows you to save maps linked to your Gmail account. I have all kinds of maps saved for my personal use.

Google has no issues with us using their map software. It is essentially the exact same thing as Google Documents (document, spreadsheet, presentation), but it is setup to do mapping.

If someone has a better setup, I'm all for it.