a) this is a wrong forum - you should have used WebCenter Content
b) I'd not say that UCM "integrates" with JDev.
JDev is just a Java IDE in which you may create a Java app that calls UCM's services (to checkin/search for content items, etc.)
Note that even in the JDev itself there are several techniques how to achive the same results - e.g. you may use UCM's Java API called RIDC, or Web Services. Myself, I have posted sample codes for both these techniques in this forum.
As for RIDC you will need to install the RIDC JDev Extension which is available from your UCM installed system (I can send you more details, if you need it).
c) to install Oracle database (which version?) follow the installation guide - e.g. http://docs.oracle.com/cd/E11882_01/install.112/e24321/inst_task.htm
d) RCU stands for Repository Creation Utility. It is a utility which creates necessary database objects (tables, views, indexes, etc.) for Oracle middleware applications. For more info, see http://docs.oracle.com/cd/E12839_01/doc.1111/e14259/rcu.htm