I think the answers to your questions will be found if you click on the link to the SOTA website at the top of the page, if that leaves any questions then please contact me by the link on the website.
Unlisted summits can be added if they are found to qualify under the prominence rule. If you find summits in your area that seem to qualify then you should pass on the information to the AM for the W7 Association, who will verify the information and add the summits at the next revision.