Re: Nvidia Xconfig difficulties
Going to runlevel 5 is one of several ways to start X.
Redhat's tools have no awareness or support for the nvidia X driver, so you'll be unlikely to obtain useful results from them in this regard.
You need to run nvidia-xconfig, or manually edit your X configuration to use the nvidia X driver.
I really think you'd be better off if you read the driver README which covers every issue that you've encountered thus far.