What folder for color sync profiles

Confused: while trying to color manage my workflow I have renamed, moved, added and deleted profiles. Now, everything is a chaos, messed up, and I would like to clean up and understand. Please, anyone:

1. Why do they call a color space a profile? (Adobe RBG is a color space, but a .icc file for a device such a printer is a profile!)

2. Where do the profiles belong? a. System/Library/ColorSync/Profiles, or b. Library/Colorsync/Profiles, or c. ~/Library/ColorSync/Profiles, or d. /Library/Application Support/Adobe/Color/Profiles/Recommended/, or e. /Library/Application Support/Adobe/Color/Profiles/ or f. /Library/Printers/EPSON/SPR2400.plugin/Contents/Resources/ICCProfiles

3. Some profiles I have downloaded have the extension .txt and not .icc. Why?

4. Can I change the name of the profiles in the Finder?

5. Can I delete profiles which I will never use?

6. Is there any way to reset (erase) and install anew from the installation DVD only the profiles without messing with the operating system (something like "check for duplicates" for the fonts...)

Sigh. Thank you.

PB G4 Mac OS X (10.4.8) PS CS2 and Epson 2400

Mac OS X (10.4.8)