I'm going to change the front brake disc rotor round things (and the pads.) I printed the applicable pages from service CD. Of all the things I've done to a car, I've never changed a rotor, but it doesn't seem too bad. Any suggestions, pointers, advice, warnings, and ideas how long it might take?

BTW got all the parts from FastLane

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5 speed '91 190E 2.6 320,000 mi. (new car, fast, smooth as silk six, couldn't find any more Peugeots)
5 speed '85 Peugeot 505 2.5l Turbo Diesel 266,000 mi. (old car, fast for a diesel, had 2 others)
5 speed '01 Jetta V6 (new wifes car, pretty quick)
5 speed '85 Peugeot 505 2.2l Turbo Gas 197,000 mi. (wifes car, faster, sadly gone just short of 200k )
5 speed '83 Yamaha 750 Maxim 14,000 mi. (fastest)
0 speed 4' x 8' 1800 lb Harbor Freight utility trailer (only as fast as what's pulling it)

The first rule of brake work is to remove the cap from the brake fluid resevour and cover the opening with a clean rag. This will prevent brake fluid from overflowing into the engine compartment.

Whether or not it is likely to overflow when you spread the calipers depends on how full the resevour is but it's always a good idea to cover it.

To remove the rotors, remove one of the bolts from the caliper and swing it up. Then I believe there is a 5mm hex bolt holding the caliper on. Take that out and tap on the rotor to free it.

The new rotors have an anti-rust covering that no longer needs to be removed. The old ones had a blue covering that always took me longer to remove than it did to change the rotors.

Don't forget to put MB anti-squeal paste on the back of the pads. Use Dot 4 or Dot 4+ fluid.

Good luck.

I know what Bud meant, but the 5mm hex key bolt holds the ROTOR on.

This job is pretty straight-forward.
I would suggest cleaning the sliding surfaces (surfaces where the metal pad backing slides in and out on the caliper) on the caliper with sandpaper, and applying a very light coating of thick moly grease (often marketed as 'brake grease').

It may also be worth checking the pins that the caliper floats on to see if they need grease. Mine were dirty last time, and binding a little. I use silicone grease here. Not sure what MB recommends.

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1986 300E 5-Speed 240k mi.

Some penetrating oil applied where the rotor mates to the hub eases rotor removal. There have been several prior threads that have discussed the final step when the rotor does not want to come off: smash it with a hammer. Post removal, clean up the mating surface and apply a small quantity of anti seize to faciliate the removal the next time around.