To get more information about a particular list, use the info command, supplying the name of the list. In this case you must contact the list owner and request the information. If you create a mailing list you will be responsible for configuring it, maintaining it, and dealing with people who abuse it. A Majordomo mailing list is not the only method available for communicating with your colleagues. The name you want for the list.
Open lists allow anyone to subscribe and unsubscribe themselves.
Closed lists have their subscriber list maintained manually by the list owner. Whether or not the list is to be 'moderated'. A moderated list requires the list owner to approve all submissions before the are sent to the rest of the list. Once a list has been created the owner is free to customize it as necessary. There are dozens of variables that can be adjusted.