Happy to hear you like the tools
Lets see if I can answer your questions:
#1 it's all controlled via the datasource; in the built in examples you can look in the persistence.xml and it is using the built-in h2 db (AS7 has H2 instead of hsql db).
#2 the connection parameters are in your JBoss configuration (if running locally look for the standalone.xml in AS7 install, if running in OpenShift look for .openshift/config/standalone.xml
#3 admin the database, you can do some tricks to get h2 expose its webui but I would recommend using mysql or postgressql on openshift - just need to add that cartridge to your application
and change the persistence.xml to use the ava:jboss/datasources/PostgreSQLDS or java:jboss/datasources/MysqlDS datasource name.
Then you can install phpmyadmin to manage things.
https://openshift.redhat.com/community/blogs/deploying-and-managing-postgresql-on-openshift shows how to do it for postgresql
hope that helps a bit ?
I have to pick my jaw up off the floor, everything you directed me to do worked quickly and correctly. Now I can see my entries via phpmyadmin. I am really impressed.
Happy to see you are impressed - hope your jaw is ok.