I have the same V12 engine in my 96 SL600. The minute a mechanic sees you, they know you have money to burn. You bought the most expensive Mercedes, be prepared to bleed. Most mechanics aren't knowledgeable in fixing this engine. If I were you, I would go to the dealer or a shop that does high end european such as ferraris, porsches and mercedes. Also being a C140 chasis, repairs are going to be expensive. Ask the dealer to do "goodwill" for you. Say the evaporator shouldnt break on a 130k car. I think the dealer will be the best place to fix the evaporator because if they break anything theyll be forced to pay for it plus they have the manual for the correct procedure.
Your thermostat can be fixed by any mechanic. Get a coolant flush too unless you have records that it doesnt need to be done. The muffler was replaced for what reason? play or necessity? If the muffler was replaced for necesity then unless the root cause of the problem wasnt fixed then it will be a recurrent issue.
By the way how much did you pay for your car. Can you return it? If you could, search for a 99 cl500 w/o ADS it would be the best. No evap problems, probably still under warranty and m119 is a very popular engine that is easier to fix than the v12. ADS is a big pain in the ass. The shocks alone are like a 1000 a peice. I am glad I'm not in your situation.