The MINIMAL System privileges for the SDE user in Oracle are these:
CREATE SESSION
CREATE SEQUENCE
CREATE TABLE
CREATE TRIGGER
CREATE PROCEDURE
SELECT ANY TABLE
However, these won't do everything you mentioned. If you want to disconnect sessions, you will need to grant DBA role to the SDE user or grant these to SDE instead:
ALTER SYSTEM
SELECT_CATALOG_ROLE
If you want to analyze objects outside of the SDE schema (user-schema geodatabases) then grant these to SDE:
ALTER ANY INDEX
ANALYZE ANY
SELECT ANY DICTIONARY
What you decide should be based on whether or not your ArcSDE administrator is the same person as your Oracle DBA.