What factors should be considered when selecting a timing belt?

What factors should be considered when selecting a timing belt?

Design Power: Motor power multiplied by a service factor.
Speeds: RPM of both the driver and driven pulleys.
Drive Ratio: Determines the number of pulley teeth.
Center Distance & Space Limits: Affects belt length and pulley size.
Environmental Conditions: Temperature, humidity, exposure to oil, chemicals, or need for food-grade certification.
Load Characteristics: Constant, shock, or reciprocating loads.
Accuracy Requirements: Need for absolute synchronization, allowable backlash.