Can only advise on a 2.4 RWD model.
Got told it doesn't need changing in normal service unless your're in there for something else. Should be good for at least 150k. That said, there have been a few with tensioner problems that have ended up detsroying the cylinder head. Ask at fords if you have a concern.
It's quite a big job to change requiring the front cover off, which is glued on. Someone else may be able to give a closer idea of time but would expect it to take at least 3 hours.
Tbird
November 2007