Yeah alot of those rear diff side seals only seep and do not need attention unless you have an actual wet drop of oil at the bottom of the housing, then you should get it resealed, but having the fluid level checked is the best way to determine leakage/loss of fluid.

That is a good paying job at the dealership, but usually not necessary in most cases.
Keep in mind, theese guys are there to make money, and they will note everything they find hoping you will bite on some of it.

Yeah ,almost every 97 E-420 I run across now days has the ears on the top of the air mass cover cracked or the rubber isolators broken where the nuts hold them down.

I carry them on my truck and usually have to order a new cover for every car I go out to.
Alot of shops put the cover on cockeyed and nothing lines up correctly and the portion that covers the air filter is usually distrorted and will not go back on right.

Sounds like you need to find a good independent that is not afraid to let you walk into the shop and have the items that need adressed pointed out to you so you can make a decision after actually seeing the evidence.