The <mx:request> tag is only necessary if you need to
send parameter to your web service. If, you query needed a key
value to use to find the data, then you would use the flex request
object to send that value to the web service's input parameter.
I haven't done a web service in 2.0 yet so I don't know what
the error means.
When the webservice call returns (Don't forget to call
send()!), the result data will be available in the "lastResult"
property. So, depending on the exact structure of the data
returned, you might access it like this: