1) you need to be a sysdba to grant sysdba:

tkyte@TKYTE816> connect sys/manager
Connected.
sys@TKYTE816> grant sysdba to scott;
grant sysdba to scott
*
ERROR at line 1:
ORA-01031: insufficient privileges

sys@TKYTE816> connect sys/manager as sysdba;
Connected.
sys@TKYTE816> grant sysdba to scott;
Grant succeeded.

sysdba allows you do to "internal" things such as startup and shutdown. it'll also avoid locked accounts (sys can be locked but sys as sysdba cannot be).



2) See above. You have to be in as sysdba to grant it.

3)

SYSOPER privilege allows operations such as:
Instance startup, mount & database open ;
Instance shutdown, dismount & database close ;
Alter database BACKUP, ARCHIVE LOG, and RECOVER.
This privilege allows the user to perform basic
operational tasks
without the ability to look at user data.

SYSDBA privilege includes all SYSOPER privileges plus full
system privileges
(with the ADMIN option), plus 'CREATE DATABASE' etc..
This is effectively the same set of privileges available
when previously connected INTERNAL.



4) I assume you are getting a VNI-2015 (error codes are important). If so:

Overview
--------
When scheduling Jobs or Events through the Enterprise Manager 2.x Console, the Oracle Management Server takes the request from the Console and submits it to the Intelligent Agent on the target server. The Intelligent Agent attempts to establish a "new" Operating System (OS) logon session for each job that it
receives. The OS logon credentials are pulled from the Console's Preferred Credentials settings. In the Preferred Credentials section, each discovered service is listed along with its service type. For OS logons, the " NODE "
service type must contain a valid OS user that has the correct permissions.


If the logon information provided to the Intelligent Agent is incorrect or missing, the Intelligent Agent will return the error:

VNI-2015: Authentication Error


Troubleshooting Checklist
--------------------------
The VNI-2015 error can occur for several reasons.

EM Console:
===========
Begin troubleshooting the VNI-2015 error at the EM Console.

1. Verify the logon credentials for the target Node and target service have been set correctly in the Preferred Credentials section of the EM Console.


If the Preferred Credentials are set correctly for the target node and the target service, continue troublshooting at the target server:

Windows NT and 2000 servers:
============================
2. Verify the OS permission 'Logon as a Batch Job' has been granted to the OS (NODE) user stored in the EM Console's Preferred Credentials section.

3. If the OMS is in a different NT domain, verify the domains can communicate.


UNIX servers:
=============
4. If the server is a Unix system, check with the system administrator and ask if any additional OS security packages are installed on the server.


5. Manually test both logons (NODE and SERVICE) at the target server.



5) load is a layer on top of sqlldr. exp, imp, sqlldr are separate tools. OEM has a gui interface that sits on top of them.