I am surprised your front pads last 100k miles.  None of the 20 or so
cars I have ever maintained (MB or not) had pads that good.  Maybe I use
too much brake?

100k miles is long enough.  It is time to replace the rotor too.  I did
the front pads/rotors on our 96 C280 18 months ago.  I don't recall
anything special.  It should be similar to the other vehicles you have done.

Below is from my memory.  Your C220 (BTW, which year?) may be different.

Typically the caliper needs to be removed to replace the rotor.  It is
secured by two bolts, possibly 19mm (or may be 17?).  Hang the caliper
with thick wire and don't twist the rubber brake hose.  Some models of
MB have the rotor secured by a small bolt, requiring 5mm hex key.

Don't forget to replace the pad sensors.  Since you are there, check the
condition of the rubber hose and the dust seal on the caliper.  Replace
them if they show age.  I always replace if it is more than 15 years
old.  Also, MB recommends flushing the brake fluid every two years,
preferably in spring.