Welcome aboard, TBT (by the way, questions about a con were why I signed up for this site in the first place, too, so settle in, buckle up and enjoy the ride
). A lot of the schedule for the con has yet to be finalized, so it's likely that we'll get that figured out in the next week or so. Also, the standard deal on signings is that there be no more than three items to sign, but in the past, Jim has said it's okay to get more signed as long as you head to the back of the line after the first three, so that everyone has a chance. He's a very generous person with signings and fan interactions, so much so that he's actually developed writer's cramp on a signing tour!
Changes may or may not be available at the con; I can't imagine Penguin would pass up the chance for bonus sales. But the "you can only get books purchased here signed" is normally the case only at in-bookstore signings.
More info as events unfold. And welcome aboard!
