I wouldn't recommend it if it hasn't leaked.
It should be replaced when it begins making a noticeable noise.
It has a chain
90,000 ks
If it is dirty, or every 2 years.
Never. This is not an item you replace at a scheduled time or mileage. It should last the life of the engine.
At around 90000km timing belt should be replaced!
It goes by mileage ....100,000 miles is recommended
Listed in your owner's manual.
120,000 miles , according to the Gates website
Timing belts for most vehicles are supposed to be replaced at 60k. Some vehicles at 90k.
If the timing belt has not been replaced during prior visits the 105k interval is when it should be replaced regardless of inspection. It should be checked at 60k and 80k for the 1.8T, and if there are signs of wear at that time replaced.
There is no set time or mileage when to replace automotive springs. It would be when springs are fatigued, cracked or broken. At that point the springs should be replaced in pairs.