Welcome to the Forums Mark!
In answer to your questions, Bill is there to sign previous purchases, tell stories, answer questions, and just plain have a good time with collectors.
An event piece is also available, in this case, Kilueha, HI. This piece is known as the "event exclusive" and is only available the day of the event. Bill is always happy to sign these as well.
It is important to note that different stores have different policies as to the number of HL's you can bring from home to be signed. It is always a good idea to call the store ahead of time to find out their policy. Also, it is always a good idea to reserve an event piece. If you are interested in one, let the store know to hold one for you, otherwise, they may sell out the day of the event leaving you without.
Also Mark, visit this link for many more helpful tidbits of event information and etiquette.
http://www.lighthousekeepers.com/forums/Forum25/HTML/000001.html I hope this info has helped.
-Todd