To answer your ownership point - the owner has set up a group list, this means that they do not need to type all the email addresses all the time. This means that he, and anyone he gives permission to, can edit that list.
For example, if I had the email addresses of all ABers, I might add them all to a distribution list and call it "AB-Members". Then, instead of having to add email addresses one at a time when authoring an email, I write "AB-Members" in the address box. This sends to all members on that list (that I previously created).
If one person, say Mr Smith, was removed from the list, he would not receive emails when the "AB-Members" list was used. However, one could also add Mr Smith as an addressee, and then he would also receive the email. Similarly, if Mr Smith no longer wanted to receive emails sent to the group list, his name could be removed and he would no longer receive them.
Email lists like this are routinely used in large organisations, where there are a large number of people and it is useful to also segregate the list of all possible employees into smaller lists. For example, there might be a distribution list called "AllEmployees" that allows you to email all employees worldwide. There might also be a subset of this list called "UKEmployees" which only contains the email addresses of the UK based employees.
Essentially, lists save you from having to type a set of email addresses each time or from having to remember all the members of a particular group.
I hope that helps.