The type on element/curriculum description is "clob", but the datatype I use in plsql *.new is "varchar" - I borrowed this concept from the forums package in order to extend the description from being limited to 4K (if I would've used varchar) up to 32K. See this thread for a little discussion about it: https://openacs.org/forums/message-view?message_id=51571
Not sure if I understand the question correctly, but I would try to use the DBMS_LOB package, specifically the DBMS_LOB.GETLENGTH and DBMS_LOB.INSTR functions. Documentation can be found on Oracle OTN.