I find my 328 a real handfull in snow. The 225 tyres really do it no favours. Goodyear eagle F1s are performance tyres and will be rubbish in the snow. If you look on the Mytyres website they have reviews and most high performance sports tyres get 1 out of 6 for grip in snow.
The grinding noise may be the ABS. It might be worth getting the traction control and the ABS checked though.
Another thought, is this the first RWD car you have driven. They require a different approach to FWD cars and demand a bit more respect.
Final thoughts, IMO 40 mph is too fast for driving on a snow covered road. I was driving in similar conditions today and I stuck to 30mph. The 360 spin could have been due to oil on the road. Like I said RWD cars can catch you out in low grip situations.
Edited by Peter Fenwick