I have 18's all around now with 8's up front and 9's in the rear. MB wheels usually have about 35mm offsets which matches what we need in the front but our cars have 22mm offset in the rear. to get the wheels out where they look best and like stock you need 10mm spacer. Spacers are not a bad thing at all if you get the ones that are machined for a Mercedes that are hub centric. I have never heard of anyone having issues with the correct hub centric spacers and correct length lug bolts. On the other hand if you use the cheap Pep boys universal spacers you are taking your life in your hands.

17" wheels will fit over the 345 or the 330mm rotors. It is the shape of the spokes that are important to clear the outer side of the caliper. I think these wheels would fit over the calipers.