Re: "(EE) NVIDIA(0): Failed to initialize the NVIDIA kernel module!" and /dev/nvidia
No, the Nvidia devices (/dev/nvidia*) are created by the installer script. Re-run it and post the log (it is in /var/log) if you encounter problems.
(You can create the devices manually with mknod, but try the installer script first.)
Also, make sure that your /etc/modprobe.conf or /etc/modules.conf contains a line that says "alias char-major-195 nvidia*" -- if not, add it and your nvidia module will be loaded automatically if needed.