A social and/or notice board and is not so much for discussing Grahams work, or related topics as covered by the other boards, but more like a place where people can share other things.
No, they don't even have to "buy" the numbers. There are tricks to let them make their call appear to be from a local number in the same exchange as your phone. Various states have laws that may be applicable, but the best thing to do is get everyone you need to communicate with in your contacts list. Then you can simply block calls that are not in your contacts, or at least force them to voice mail.