As far as i was aware if the car has the screen in the front dashboard then it will have sat nav. This is unless an aftermarket piece of kit was put in. If you check in the boot in the left and right sides you should find the cd changer sat nav and battery behind some fold out pannels. I would imagine though that if there is no disc in the system than the sat nav will not work.
As for your recent purchase, what a great car you will be very pleased and performance is not that far off an M5. The steering is not as good as the 6 cylinder cars as in order to get the V8 lump in a worm and roller system had to be fitted, but if you have come from an e34 you won't even notice. Brakes are awsome and will wind you in emergency situations and handling is great. However they can be quite twitchy in the wet if you turn all the traction bits off.