Did eminem used to be a police officer?
No. Eminem spent some time working in a restaurant, cooking and washing dishes. Those were the only jobs he held before becoming a mainstream rapper.
In the USA you can address a police officer as 'Sir' 'Ma'am' or 'Officer' when you are talking to them so how do you address a French Police Officer when conversing with them?
yes because if a police officer is off their shift and are speeding they can get a ticket anyway. The average citizen does not have the legal authority to issue a ticket to anyone, police officer or regular citizen. A police officer can issue a ticket to another police officer who is violating the law while not in the performance of their duties.