I did FP in Cleveland, OH. I am not sure whether there are any specific dates for each INS local office. Also, it was mentioned in my FP notification sent by INS that if I am not able to make at particular date then I can visit on any consecutive Wednesday, please check the same in your notification.
Regarding forms, it would be done at INS local office. I think it would be better to visit your local INS office once with your query and see what they have to say....
Hope this helps and sorry for delayed reply.