Those guys usually speak english, so it should work
Important things: a) Lights b) Exhaust and emissions.
a) Swap your headlights and rear lights with european market 2nd hand lights for your car. Problem solved.
Does your car have side markers? If it has side marker lights, then those lights must be disabled for the german streets, while sidemarkers are not allowed around here (just kick out the sidemarkers lightbulb).
b) Put your cat back into the car or swap the whole exhaust for a european 2nd hand stock exhaust for the emissions test. Then it shouldnt be very hard to pass any tests.
What wheels and suspension do you have?