I haven't had the alternator out, but I've had a really good look at one.

As far as I can tell, it's two bolts from the front, and the alternator should slip back, down and out. (after taking the tension off the belt of course)

There are two E300's in my neighborhood. The other is a partner at my wife's law firm. I offer to work on that car from time to time. If I don't have enough time, then I'll help diagnose, and send them the right direction.

It is a 'very expensive' alternator. Yes, there is some sort of clutch in it.
Other than the clutch, I consider it a conventional looking alternator, that an average rebuilder could probably handle.

If you're anywhere near Lancaster County PA, I've had excellent luck with Weaver Bros, rebuilding an old (not quite unobtainium) 914/6 alternator. I think they could probably handle anything.