Know whatcha mean on those tires... Just FYI: Tirerack has a KILLER deal on Michelin Pilot MXM's in 225/50/16, which is my fav 400E "plus" size. $137 a tire on sale (normally they are anywhere from 170 mailorder - 200+ retail OTC)
When my power steering was leaking (it "lost" fluid VERY slightly for awhile first...might notice a .5 cm. drop in fluid level, but never anything else in a 1 month period) When the leak got to the point of noticing it would wet the undertray, suspension, etc but never make it onto the ground/driveway. If yours is spotting the driveway, it may be a sooner rather than later item. Have you noticed how much P/S fluid your going through?
The sunroof paint difference is something I see on MANY W124's. Doesn't matter if it is original paint, repaint, whatever...it just does not age as well on the sunroof. Almost looks like little acid rain pits. The cloudy usually responds to some Meguiar's #9 and #7 + some Gold Class, but the "pits" are not as easy to dispell. Are the cloudy areas raised, or sunken/into the paint. If they are raised, a clay-cleaning bar should work wonders for you.
Talk to you later...Lee