What are all of the preferences files used by iTunes X and iTunes XI? Excluding anything in the iTunes Library, what and where (or full relative path is fine) are all of externally called files including preference list files etc used by iTunes X 10.6.3? And by iTunes XI 11.2.1? 

A comprehensive and exhaustive list of what files these 2 separate versions of iTunes access, excluding the iTunes Library and anything inside the application bundle is what I'm after. If they both use identical external files to store their preferences, all the better. If you can give any short explanation on each file, what is stored there, it is also appreciated.

The purpose of identifying these files is to aid in the understanding of how to go about having both versions of iTunes installed at the same time, so that I can choose (via a switcher script that may shuffle the files in and out of the correct place) which version to load for the purposes of enabling administration of older iOS devices that are no longer supported in the current version of iTunes.
This answer is in two parts. If you're after all the preference files associated with iTunes then the list is relatively short. If you want every file that iTunes accesses then the list is going to be vastly and incredibly long and also very difficult to track down. If you can offer some more context of what reason you're trying to track these down maybe I can help you isolate files related to your needs.

All of iTunes preference files:

File (Primary): com.apple.iTunes.MACHINE_GUID.plist

Located at: /Users/USERNAME/Library/Preferences/ByHost

Files: com.apple.iTunesHelper.plist | com.apple.iTunes.plist | com.apple.iTunes.eq.plist

Located at: /Users/USERNAME/Library/Preferences

Hidden File: .iTunes Preferences.plist

Located at: /Users/USERNAME/Music/iTunes/iTunes Media

All of the settings you set/change in the iTunes application are represented in the two primary preference files. The one in the ByHost folder above and the other main one called com.apple.iTunes.plist above.

Hope that helps.