YES it's worth it. Anyone who tells you otherwise is a crook.
Normally it will last the life of the engine and is replaced when the engine is overhauled.
It doesn't have a timing belt. It has a timing chain and it will last the life of the engine.
No. But if the pump is driven by the timing belt, it is good practice to replace the pump at the time of installing the engine. A pump failure will cause the timing belt to jump. In the majority of cases this will cause valve to piston contact. Plus, if the part is hard to change, maybe you should do it now rather than later, when it will be much harder to get to.
Never, it is designed to last the life of the engine and is normally replaced when the engine is overhauled.
The timing chain will normally last the life of the engine and is replaced when the engine is rebuilt.
It has a timing belt.
Timing chains normally last the life of the engine and are replaced when the engine is rebuilt.
Timing chains should last the life of the engine and are normally replaced when the engine is rebuilt.
Should last the life of the engine and be replaced when the engine is overhauled.
Timing chains are designed to last the life of the engine and are normally replaced during a complete engine rebuild. Unless it gets noisy there is no need to replace it.
It should last the life of the engine and is normally replaced when the engine is overhauled.
Normall it will last the life of the engine and is changed when the engine is overhauled.