You can issue SQL queries to the database from the Corda shell with the jdbc command
The config file format supports many useful features: https://github.com/typesafehub/config#using-hocon-the-json-superset
You can chat to the Corda team using Slack: https://slack.corda.net/
Administrator users can be granted access to do everything by granting them the ALL permission
If you don't wish to use the shell it can be disabled with the --no-local-shell flag
Use the "flow watch" shell command to see what flows your node is running