What i know from research and having to buy all the ms6 front end parts, it is NOT directly interchangable. To begin with, the bumper reinforcement is bigger on the ms6 than it is the m6. Secondly, to have the ms6 bigger hood, you need the ms6 fenders as well. Im sure the m6 front bumper would fit with these parts, but it would look way off. The only interchangable parts are the headlights, the only difference is the HID and non HID, and the radiator core support, all the rest of the front end stuff would have to get changed. All that stuff is pretty pricey and super hard to find other than the dealer, which charges an arm and a leg. Hope this helps.
Yes, the tails are interchangable.