If you did something like 'cp /etc/X11/xorg.conf /etc/X11/xorg.conf.backup' then you have a backup. Do a 'ls /etc/X11/' in the terminal to see.
Now that I look in Synaptic, I don't have nvidia-settings installed either. I guess it was included in the driver that I have. Which version of the Nvidia driver are you using? You must have an older version, I have 1.0-9629.
As for your last question, I have no clue. As I said in my last post, I have never tried this before. The resolution that I want was already in Ubuntu's 'Screen Resolution' thing. It's worth a shot, though.