I tow a 1500kg Burstner with an E220 cdi auto without any problems except getting the noseweight down to 75kg. On this basis you should be fine. The auto box (Tiptronic) is very good and is easy to override manually - very useful for long descents. Fuel consumption depends on how heavy your foot and the prevailing wind. At 50 mph in calm conditions I can get around 27 mpg - it seems to be improving as the engine beds in - only 13,000 miles at the moment.
If you have an auto box and tow a lot, think about getting the transmission fluid changed earlier than the 'book' suggests.