concerning db_load_sql_data:
Seems as if the following sequence leads to the problem
set fd [open "|[file join $env(ORACLE_HOME) bin sqlldr] userid=$user_pass control=$tmpnam" "r"]...
close $fd
Do you have the sqlldr under [file join $env(ORACLE_HOME) bin sqlldr]?
Are the provded parameters ok (e.g. the $tmpnam)?
Concerning (d): You are using the head version of categories, where it seems, that the column "widget" was not added in the Oracle version. Although i hate add something to CVS, which i cannot test, i added the column in the Oracle creation procs. Please get the head version from CVS and test it with Oracle. If the error is gone, i will apply the same fix to the oacs-5-4 branch, which has apparently the same problem.