In regard to getting your xorg.conf file to set the resolution of the GUI, try this
Section "Device" Identifier "Configured Video Device" EndSection Section "Monitor" Identifier "Configured Monitor" HorizSync 30.0-62.0 VertRefresh 50.0-70.0 EndSection Section "Screen" Identifier "Default Screen" Monitor "Configured Monitor" Device "Configured Video Device" DefaultDepth 24 SubSection "Display" Depth 24 Modes "1024x768" "800x600" EndSubSection EndSection
change the Modes "1024x768" "800x600" to whatever video modes you want to be your possible video mode resolutons. Be sure to reboot your machine after making this change to xorg.conf tho. I would also backup xorg.conf before you make these edits by doing
sudo cp xorg.conf xorg.conf.backup
in the /etc/ directory of course