You can have a hard time insuring such a car if you are 'too young'. Most insurance companies refused when I bought the CSi at the age of 24.
When you are 26 and older there should be no real problem, although some still won't provide full coverage (namely those who brag so much on TV about their low, low fees).
I don't know if being no german citizen and not living for at least six month a year in Germany could be a problem.
However, if you want the lowest insurance fees for an 8 series and still have all the coverage you want, try
DEVK (I am in no way associated with them - they have simply the best offers to make).
Good luck...
...Mike