Audi A4 from Spain - Used Car for Sale

Hello,

I know this is off-topic. Please delete the thread if it's unwanted.

I found an A4 131PD. The car is from Spain, it's already 12 months old and has 29,000 km on the odometer, so it's a used car (according to German law, a car is no longer considered new if it has more than 6,000 km or is older than 6 months).
Can I register this vehicle here without any major problems?
Do I need a new registration document? A friend who works at an Audi dealership told me that they often deal with Italian vehicles and that the vehicle's registration document is valid here. Since Italy and Spain are both in the EU, it should work out, right?
Gibt es sonst noch was zu beachten ? Exhaust emissions: Euro 3?
I've also seen a Ford Fiesta from Spain that didn't have any underbody sealant or cavity protection. Is it the same with Audi?
It doesn't seem to be a problem with Skoda, as my wife hasn't noticed any difference between her FABIA and one purchased in Germany. (This one is also from Spain).

Does anyone have experience with importing used cars?

THX