Hi, we are updating the Designer documentation and you can see the latest here: https://hudson.jboss.org/hudson/job/jBPM/lastSuccessfulBuild/artifact/jbpm-distribution/target/jbpm-5.2.0-SNAPSHOT-docs-build/jbpm-docs/html/ch10.html. As far as the properties, this is still on the todo list and will be available in the docs before the jBPM 5.2 release. For now if you have any questions this is a good place to ask
Hope this helps and thanks for using the web designer.
Another place to look is BPMN2.0 specification that describes the available properties of all constructs. Since web designer is implementing the spec I think it is a good start to be familiar with it but of course some documnatation is always welcome.