When you post a question like that, it's best to clearly state the year and model, or else have it in your signature. Digging through your profile I see a 1994 E320, so we'll assume that is it.
The W124 has the evaporator buried way down under the dash, so the whole dash has to come out. Yes, you should go ahead and replace all the vacuum pods while you're there. Just call Phil and tell him you want all the pods - he'll know what to do.
The Nippondenso has teflon coated pistons that spread "black death" throughout the system when the compressor goes. Because of this and the reason mentioned above, avoid the auto parts store compressor. Buy one from Phil. Obviously the new is a good choice, I haven't heard anything about rebuilds from here.
Another alternative to explore for the expensive and labor-intensive parts is the dealer. MB parts carry a one year parts and labor warranty, even if they did not do the labor. You put in a compressor, it fails within a year, they replace it including labor for free.
No, I don't think you're nuts. The car is worthless in Florida without air. If you and your friend can get this job done right, you'll be able to enjoy the car for a long, long time.
82 300D Euro
12 Honda Pilot
14 Tesla Model S
Former MB: 86 190E 2.3, 87 300E, 80 240D
Chain Elongation References