How do the orders get to my restaurant ?

orders are sent by email.
the information that will be received in each email will depend on your settings in WPPizza -> Templates -> Emails (Tab at the top)

if you need them to be sent by fax for example you will have to look into integrating your orders with an email2fax gateway (search for it on your favourite search engine)

you can perhaps also integrate some other custom solution, based on the “wppizza_on_order_execute” action hook
see :

furthermore, there is also the “WPPizza Google Cloudprint” extension available if you want to send any orders directly to a cloudprint enabled printer.