Hello Ashish, thank you for your reply.
ad 1) I didn't created a datasource explicitely, should I? As mentioned in my initial posting, I just added guvnor-distribution-5.5.0.Final.zip and jbpm-designer-2.4.0.Final-tomcat.war in my Tomcat 7.0.41 webapps directory, did some renaming (drools-guvnor.war and designer.war) and did some minor configuration change in designer/profiles/jbpm.xml to use port 9090, which my Tomcat is running.
ad 2) Where do I find this properties file?