That's an awesomely helpful accounting of your experience, thank you!
So I read the attached link and the part that says the member did not have to remove the bumper to remove the headlight assembly on their W220.
I just watched a detailed video on Youtube about an owner removing their front bumper on a 2007 W221, removing the headlights and reinstalling everything. According to the video and the close up of the sides of the headlights, there is a torx screw stud that attaches along the side of the headlights that cannot be accessed unless you remove the bumper cover. That is probably why there are so may headlights for sale on Ebay with broken mounts because not all of the screws and bolts where removed before someone grabbed the assembly and pulled it forcefully to remove it.
If you watch the video I don't see how you could remove the headlights otherwise. That said, I know that my bumper cover was repainted when the dealer repaired my car well before I bought it so arguably all of the mounting screws and bolts should come loose fairly easily. I don't plan on removing the entire bumper cover and unplugging all of the parking sensors, headlight washer connections, etc. so I will have to rig up something that will allow me to pull the bumper cover out just enough to access all the mounting screws for the drivers headlight.
I believe I read the headlight washer pickup tube can be unhooked by turning the connection 90 degrees and pulling it free. If anyone has does this and that is incorrect please let me know asap so I don't snap something off or end up with a geyser of a leak from inside the bumper cover should I find the need to wash my headlights while driving.
I did purchase all three (3) ballasts that were confirmed to be in working order and tested with refund policies within 30 days or longer. I have been told various versions of which ballast controls what, but I think I am going to end up doing a plug a play until not only my low beam functions again, but also the active intelligent light and cornering light on the left side start working again. I am assuming that the malfunction in the cornering light and active lighting is directly related to the low beam not working, but I don't want to just replace that ballast, bolt everything all back together and find out my cornering light and the active lighting feature are controlled by one of the other ballasts.
Finally, I have read up on how to disconnect the battery and discharge the any stored electrical charge before removing the headlights. Is there any need to have my vehicle scanned after I reinstall everything so my Command System recognizes the new parts? Or will my computer scan everything connection, recognize the parts as OEM MB pieces and function as normal?