Mazda B2600 Engine Problems
Chain or belt in 2003 Mazda Bravo
It has a belt to drive the camshaft, and belts typically are changed every 100,000 km or so, but because they deteriorate with time there is usually a time recommendation for the service as well. That's in the order of four to five years, and as your Bravo is seven years old it would wise to change it.
Warmup bravo to avoid noise
I agree with Mazda. It's a function of the high idle speed during the cold phase. I wouldn't worry about it and I wouldn't sit for two minutes on a cold morning so I can engage reverse.