Rodinal

I have a non-functioning transmission module (see picture from the scanner).

First question:
The car does behaves just fine. What's the inconvenient of having that part not working? How long can I go without it? Am I about to bust something else as I continue without it?

Second question:
Does anyone know the MB part number? There seems to be the 722.8 and and 772.9. which ones goes on the 2006 R350 ?

Third question:
Any good on-line place for that?