First complete 1Z0-007, this covers the SQL part, "Introduction to Oracle 9i SQL" is a good book for this certification. I think the author is Couchman. Then you can go for the PL/SQL version of the exam.
Time required for the preparation of exam varies for each person, depending upon his skillset, experiance etc .. If you have working experiance in Oracle then 1 week should be enough to clear the SQL part.