Benzmac and / or M.B.DOC recommends changine the tranny fluid at 60,000 miles.
The FSS system requires that you use synthetic.
The early engines ('98) had problems with the harmonic balancer. The flaw was corrected on later engines. Yours is clearly way past this so it is o.k.
As for your initial checkup, I'd feel comfortable taking it to a good Mercedes Benz Service and Repair facility or the dealer.
Do you live in So. Cal. or No Cal.? If you live in So. Cal., I recommend taking the car to Enrique at Mr. MB Motors in Tarzana. He is world famous, and there are many posts recommending him on this site under the Good Shops section.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".