that is impossable to answer. life of belt all depends on how much the engine is run
No, an accessory belt is not considered a serpentine belt. However, a serpentine belt is considered a specific type of accessory belt.
The serpentine belt is a long belt on the front of the engine. The belt goes over a number of pulleys and powers many things such as the alternator and power steering all at once. The twisting and turning through all of the pulleys like a snake is how it came to be called a serpentine belt.
Serpentine Belt Diagram ML320
Serpentine belt, no. Timing belt, good chance yes.
If the alternator belt is the same belt as the other accessories, yes.
That I know of, there is NO serpentine belt, unless you are talking about the the Timing Belt (hardly serpentine, but anyway), it has a belt tensioner, not automatic, though.
If you do the labor yourself, the last belt I bought cost around $45-50.
Loosen the tensioner pulley. Slide the tensioner pulley to the right. The serpentine belt will come loose. Remove the serpentine belt. Reverse the process to install the new serpentine belt.
It is a serpentine BELT , not hose.
Away from the serpentine belt
You can change the serpentine belt by loosening the tensioner pulley. When the tensioner pulley is loose and the serpentine belt will become loose. Put the new serpentine belt on and tighten the tensioner pulley.