On a 500E, you'll need to adjust the SLS to get the rear end dropped. And, you may end up using the thickest spring pads up front, with thinnest in the rear. At least, that's what I had to do on my car... ended up pulling the springs and going back to stock after a year or two.
The camber arms are mostly needed if you have rear wheels/tires much wider than stock, as the negative camber will destroy tires rapidly. It's less of an issue on the stock 16" setup. I like to shoot for -1.0° in the rear when aligning; note this will make the rear end "looser" when pushing hard in corners. Stock negative camber when lowered can be nearly -3.0°!