Transformer required or not?

I am trying to integrate MQ Series and external web service. Mule should pick up plain XML message from the queue and forward it to the web service. Finally Mule should put the response back on queue. Do I need a transformer? I don't have the environment to test this right now, just trying to come up with the configuration doc for the above scenario.

Web service is SOAP based. Mule should be able to form a request from plain XML on the queue. Am I right?
Another thing is I am trying to create a mock web service hosted inside Mule. Just in case if the external web service is down I want to continue my testing using this mock web service. Please let me know if this mock behaviour can be achieved in any other way (besides just writing a SOAP web service inside Mule from scratch).