RMAN full backup or full with level 0 backup ..?

I think your a bit confused. You don't configure your database for backup
you specify how you want to back up your database.

The first chunk of code is an exmaple of doing a full backup via rman and
the second example is doing an incremental backup with rman.

You can read the RMAN documentation to see what the differences are
and how to setup a catalog to register your backup's if thats what you
want.

Good luck

rman < connect target sys/sys@GOLD_PRI
connect catalog rman/rman@GOLD_CAT

CROSSCHECK BACKUP DEVICE TYPE DISK;
CROSSCHECK ARCHIVELOG ALL;
RUN {
SQL 'ALTER SYSTEM SWITCH LOGFILE';
BACKUP INCREMENTAL LEVEL 0
FILESPERSET 2 DATABASE
INCLUDE CURRENT CONTROLFILE
PLUS ARCHIVELOG DELETE INPUT;
}
DELETE NOPROMPT EXPIRED BACKUP;
DELETE NOPROMPT OBSOLETE;

EOF

rman < connect target sys/sys@GOLD_PRI
connect catalog rman/rman@GOLD_CAT

CROSSCHECK BACKUP DEVICE TYPE DISK;
CROSSCHECK ARCHIVELOG ALL;
RUN {
SQL 'ALTER SYSTEM SWITCH LOGFILE';
BACKUP INCREMENTAL LEVEL 1
FILESPERSET 2 DATABASE
INCLUDE CURRENT CONTROLFILE
PLUS ARCHIVELOG DELETE INPUT;
}
DELETE NOPROMPT EXPIRED BACKUP;
DELETE NOPROMPT OBSOLETE;

EOF