I'll try to answer your questions before you do ;-)
Altough the examples do not exercise it, the invocation subsystem is practically complete. There are a couple of test suites that demostrate it, altough you have to set them up manually.
Wait 1-2 business days for alpha 4 to be released
Go to test/webservices/translator
Edit build.properties to match your environment
Run target deploy of build.xml
Go to the base directory
Run target test.server
PortCallerTest exercises one-way, request/response and request/fault scenarios for both RPC and document styles.
In fact, simple and complex types are treated the same way. Elements are a slightly different animal. In the end it's just a matter of copying data from the process variables to the right parts of the SOAP envelope.
Your last question left me thinking. From my last reading of the SOAP 1.1 spec and WS-I BP 1.0, setting a name for the input and output of an operation has no effect on the SOAP envelope. The operation wrapper is always named just like the operation in the request message. For the response, the operation name has a "Response" suffix. Did I miss anything?