Yes, you can control both the speed and direction of a gear motor. Using a motor driver or controller, you can adjust the voltage supplied to the motor to control the speed. Additionally, by reversing the polarity, you can change the direction of rotation.

The noise level of gear motors can vary. In general, gear motors are designed for quiet operation, especially when compared to standard motors. However, the noise can depend on factors like gear type, quality, and load. If noise is a concern for your application, consider choosing gear motors with noise reduction features.

Gear motors are designed for durability, and their lifespan depends on factors like quality, usage, and maintenance. Choosing high-quality gear motors and using them within their specified limits can contribute to their long-term reliability.

Modifying gear motors is possible, but it requires a good understanding of their internal workings. For customization, consider choosing gear motors with features like replaceable gears or encoders. Always follow manufacturer guidelines to ensure modifications do not compromise performance or safety.