Wanted to do a Trans service, what type trans fluid, how much fluid, anything special needed?
Welcome, Derek. Please click the User CP link and complete your BW profile re: vehicle and location as that is often useful information.
Kudos for wanting to change it.
If all you're doing is a pan drop and filter change then you'll need the filter kit, 4L of MB fluid for the 5-speed transmission, the trans dipstick tool and ideally, an IR thermometer to be sure the fluid is at operating temp to set the final level. Follow the DIY procedure in the W210 forum, same transmission and procedure. Only add 3L on refill, then set level by adding at the 25C level on the stick. Bring it to operating temp, then set the final level at 80C.
If you want to change all of the fluid then do the basic change, add 8 more Liters of fluid to your purchase, and then use yumling's DIY to flush the fluid through the cooling lines using the pump in the transmission.
Take care and enjoy the ride,