I'm afraid that web services are not working properly with version 4.11 server. Please try 4.10, but don't delete 4.11, as it has useful examples. The following are only suggestions, if you think of a simpler solution you are allowed (and encouraged) to use it:
1 - Unmarshall XML: use smooks.
2 - Splitter and Aggregator. You may write your own splitter. Check the streaming_aggregator example, the java class IncomingComposer (version 4.11). The difference as I explained in the class is that there is no final message to count the previous ones. Each message carries the total number of messages.
3 - Process details: check bpm_orchestrator4 (and the easier ones 1,2 and 3 before).
4 - Make the process reply: use <property name="reply-to-originator" value="true" /> in the action <action class="org.jboss.soa.esb.services.jbpm.actions.BpmProcessor" name="..."> of jboss-esb.xml. This requires that the process also uses <action class="org.jboss.soa.esb.services.jbpm.actionhandlers.EsbNotifier"> at some point (typically in the end). Again, this is done in the aforementioned examples (bpm_orchestrator4).
5 - Creation of web services and utilization as wrappers of the EJBs: in this blog message.
6 - Invoke web services: see example webservice_consumer1 (we may also see the others and use their approaches). You may also want to take a look at webservice_producer.
Don't forget to download the Programmers guide, from here.