"Dispwin: Error - Failed to get the displays current ICC profile" ..which is my main question. How is "dispwin -L' supposed to find the ICC profile, the one I initially installed by doing "dispwin -I path-to-file" ?
On Linux, dispwin installs the profile either to ~/.local/share/color/icc/devices/display/<profile.icc> or, if you use sudo and dispwin's -sl option, to /usr/local/share/color/icc/devices/display/<profile.icc>The profile location is written to the file color.jcnf, which maps displays to profiles.
That file is in ~/.config/ or (with sudo dispwin -sl) in /etc/xdg/(actually, dispwin uses XDG_CONFIG_DIRS and XDG_DATA_DIRS to determine the directories)
dispwin -L reads the color.jcnf to load the correct profile. I don't know why it doesn't work in your case, though. You can check the above directories and color.jcnf to see if the profile was correctly installed.
(as a side note, I'd do dispwin -c -L, which clears the calibration before loading it from the profile, instead of just -L. Although I don't think it'll solve the issue you're having, it's still a good idea)