IBM supplies JDBC drivers for the iSeries and DB2 is the built-in database. There's no real difference between using JDBC to interface with an iSeries machine and using JDBC to interface with any other database/OS.
For details, check out the docs at ibm.com.
"privilege" comes from the Latin words for "private" and "law" (legal) and dates to feudal times. To "claim privilege" meant that you were above the laws that applied to the common people.