In the Live Agent Developer Guide, Chatper 5 addresses routing Live Chat based on a value selected on a field on the pre-chat form.  The example has a "department" field.  In the pre-chat Visualforce page, the values in the department field are mapped to specific Chat Button ID's.  So there is 1 chat button on the website.  When clicked, it prompts with the pre-chat form.  When the pre-chat form is submitted, it determines routing based on the selection made in the department field. 

Question 1:  Is the 1 chat button on the website ALWAYS available -- even if there is no agent available in any of the queues?
Question 2:  Is there a way to exclue values from the dropdown list if there is no agent avialable in the corresponding chat button queue?

Does anyone out there have a Live Chat form that handles routing that could comment on your experience?