Just made an appointment to get the coolant changed finally. After all the great advice form all of you I ended up buying the following:
Red Line Watter Watter $10.49 from Canadian Tire
Prestone Super Flush $3.99 from Canadian Tire instead of MB Citric Acid $24.00
Distilled Water $2.97 from Wal Mart
Mercedes Benz Thermostat $23.04
Mercedes Benz Antifreeze Yellow/Orange
I'll take a good look at the hoses when I'm there to see if I need to replace any them.