1. You would use your original lugs rather than the one's from the E90. The numbers pertaining to the lug bolts tell you what the diameter and thread width are: M14 x 1.25 = Metric, 14mm diameter, 1.25 mm width per thread. So an M12 x 1.5 is a smaller diameter bolt with larger threads, and won't fit your wheel hubs.
2. All BMW 3 series (iirc) wheels are 72.6 hub, 5 x 120 bolt pattern, so the wheels will fit. The ET is the measurement of backspacing, so they are within 2mm of each other, and I can't guarantee it but I doubt that will cause any rubbing.
3. The tire size on the E90 wheels will work, but your speedometer will be off due to the smaller diameter wheels. At 60mph on your speedometer, your actual speed would be about 57.6 mph; so the effect is about 2mph off at 60.
http://www.paspeedo.com/calculator.htm
EDIT: aloha posted while I was typing
