Hi, I used the Sybex books, but that was for Oracle Release 9i. Back then it required two tests to pass to become OCA - 1Z0-007 and 1Z0-031 - now it's "just" one test for 10g. If you're looking for good database books I can personally recommend all books by Thomas Kyte, such as "Effective Oracle by Design" - he'll help you avoid common mistakes on every-day problems like resultset paging and the like. Afaik is this Tom "the Tom" behind asktoms Oracle questions.
SQL and PL/SQL will get you an OCA, to get an OCP you need Oracle Forms.
As (presumably) a Java Developer I would be surprised if you wanted to study Forms - especially since Oracle seems to want to move existing Forms developers to JDeveloper and ADF Faces.
I suggest you browse the site and come back with any questions.
As far as 9i being out of date is concerned, I recall seeing a statistic saying more than 50% of Oracle databases are still 9i, but on the other hand 11g Beta is now available. It doesn't affect your choice of Developer Certification - I don't believe there is a dedicated 10g version.