(1) Sedans and wagons are the same: they both have the 41mm and 46mm nut (36 and 41mm was the wrong size, sorry). You'll need wrenches, not sockets (eg
http://www.samstagsales.com/mercedes.htm#drive sells them, but they are too pricey IMO).
There is a pdf manual that you could download (
http://mb.braingears.com/124_DISC2/Program/universal_shaft.htm file: 41.050pdf, p. 22ff - it is a 23 MB file, youl'll need broadband access.)
(2) Yes, I would include a new rear flexdisc - I had to destroy the one that was one my car. Nothing else I can think of at the moment, maybe parking brake cables.
Good luck, Bruno