Ford Crown Victoria P71 conversion for Germany

Hello everybody, I have a few questions and I hope this is the one or the other that can help me. I’ve been playing with the idea of getting a US car for a very long time now and now it’s time. I’m looking for the US market now and if I get the right Ford Crown Vic model in front of my face it’s going on. I already have a company that does the purchase and transport for me in the USA. What I have to pay here at customs and taxes I know a uch. And now to the problem. Can I upgrade the car, a Ford Crown Vic P71 from ca 2008 by myself? What does everything have to be converted? Sure turn signal, stand light and fog-stop light on everyone but anything else? Do I need special documents to which I as a private person might not get to? Does one of you have experience? Is there perhaps even one of the people in Hesse who has done this with the TÜV already with this model? But I have to ask questions about this, because unfortunately I couldn’t find anything really helpful on the net. And you can’t believe everything on the net anyway. That’s why my call for help to all Crown Vic owners. I am grateful for every tip and experience report when importing. Maybe even a little bit, because logically the P71 models ex Police or other state vehicles were missing here and there sometimes something about parts like e.g. the front inner light or back also often the Window lifter switch. Where is it easiest to get it? Thank you for your time and help. Greeting Matthias