Very belated, but here's the answer - you may want to confirm this using your own Config.ini file from within the Race07/GTRe folder:
Sounds, Locations and Talent directories all go under the Gamedata directory, as with previous sims based on this engine - I had to create Gamedata before I could put them in it.
Teams (i.e. add-on cars) go under the ROOT - i.e. at the same level as Gamedata and the Race07 executable folder.
So, for example, I have:
...\Race07\teams\GT_Pro_Addon\ALZEN Porsche
...\Race07\Gamedata\Talent\*.rcd (drivername.rcd)
...\Race07\Gamedata\Locations\LagunaSeca
Repaints for default cars simply drop the file in the "CustomSkins directory, apparently. They should apply to a car automatically. Er... Yeah. Right. I've not tried it yet, but that sounds unlikely at best!
So far, everything I have installed works.
Hope that helps!
Ian P.