Many of our Hummingbird components are uniquely compatible with the Hummingbird controller while others are not.
Our sensors are uniquely engineered to produce meaningful data (common units of measure) in each of the programming environments, and we know that the voltage requirements are compatible. Basically, we have done the breadboarding for you with our sensors, so you don't need to add a resistor or anything like that. You can use other sensors, but they must be analog sensors that take a 3V supply. You would need to look through the datasheet for any additional circuitry requirements, so using third-party sensors is a little tricky.
Other parts like the LEDs and servos have not been altered and are more commonly available. Third-party LEDs and servos should work just like our components when you use them with the Hummingbird controller. Servos need to use a 5-6 V supply and require less than 2A of current (that is most hobby servos, but avoid anything labeled high torque).