Brake Pad Replacement - 1999 E300 (210)

Yesterday, the maintenance display on my 1999 E300 showed that there was a brake wear issue. (The car has @56,000 miles) I have changed many shoes and pads on cars and truck (mostly GM products), but never on one of these or any other Mercedes. I have been searching posts, but I am having a hard time finding everything that I have in question; so here is my list. I did pull one of the rear wheels to determine that I have the single pin type pad. Thank you in advance for your assistance.

1. Are there brake wear sensors at each wheel? I want to know how many of these I may need to purchase.

2. Is there a detailed post for replacing the front brake pads? If not is there anything specific to this car I should about replacing the front pads? I know that the rear pads have a retaining pin. Do the front pads have a retaining pin and if so how is it to be removed? While replacing the pads should I repack the front bearings and if so how do I go about that job? Is there recommended grease?

3. Is there a detailed post for replacing the rear brake pads? If not is there anything specific to this car I should about replacing the rear pads? How do I remove the pad retaining pin?

4. In searching brake pads on the web I have found that most do not provide information on the composition of the pad material. I would like to try ceramic pads on the front in hopes of keeping the front wheels cleaner. Does anyone have any suggestions on where and what brands are available in ceramic?

Again, thank you for assistance.