1) I plan on having 4 WD hard drives mounted in this case....
2) Will my 4 hard drives be creating sufficient heat to justify the extra fan?
3) Any opinions for a newbie just looking to quiet his system down to a resonable level would be appreciated.
welcome to spcr!
WD's are among the loudest. That will be your #1 challenge. Even 4 Barracuda's would add up but 4 WDs -- that's much tougher.
2) Probably, but you can run that 12V fan (whatever you choose) at a very slow speed (the PSU fan output would probably work fine)
3) Go with fewer, larger Barracuda -- or if you want better performance -- Hitachi/IBM 180GXP drives. Also open up the Sonata bezel and cut away any unecessary plastic on the inside to enlarge the intake vents. It helps with both airflow and turbulence noise if you have significant airflow. Doesn't change noise appreciably.