The Plaque actually is from the E36 LTW/GT.
AS Jbird said, UK cars had a different plaque but this was a dealer effort, meaning; Uk dealers installed them after delivery, it wasn't a factory option. Still jealous though
About the Bootfloor, its a inherent design flaw on the E46, every model will develop cracks sooner or later.
Spotting the cracks from just looking underneath the car isn't really possible. If theres cracks visible without removing the rear axle its already in a terrible state.