You can jump your PSU and check the fan system without concern of damage (assuming a quality PSU here). If you add fans with led's on a three pin connector the led's may not work well (might be dim or not work - I'd not heard of blinking) below max setting. The reason for that is the controller changes the voltage to the fans to control their speed, the fans don't mind but led's do. If the case controller can use four pin PWM connections and changes fan speed through a PWM controller, you shouldn't have that issue (I don't think it's likely though). BTW, it shouldn't harm the led's either
Hope it helps
its 3 wires, one of them is a Y .. makes it 4.. but if i Y up the 2 first wires.. then i can fit 6 fans there...
the cooler master sickle flow is 99% in looks to the 2 stock leds fans that the trooper comes with