1) To run that nvchooser stuff you need to do: sh NVChooser.sh in a console.
2) The drivers default to (/etc/X11/)XF86Config-4 if that doesn't exist it looks for XF86Config in that dir. (if that doesn't exist it looks in various other places but it is there) If you really want the logfile it is in /var/log it will be called something like xfree86.0.log
3) You can't use the example XF86Config file from the drivers because that one isn't meant for your system. The most important thing that isn't for your system are the monitor settings and some other things. So using it can be dangerous. Just edit your current XF86Config-4 file.