This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
No, both are not required.
If you declare the style to be RPC in a <soapbind:binding> element that is a child of the <binding> element, then it applies to all the operations of the binding.
You can then declare the style for an individual operation if you want to override the above mentioned setting.