IMO, knowing the frequency response of the sensor is certainly important. The specs of .001 Hz to 1000 MHz seem near impossible unless backed up with a detailed amplitude VS frequency response chart.

Yet I might choose that sensor for an initial build. Since the freq-response of the sensor is so wide, and since the transducer resonates at or near 40 kHz, I'd be fairly confident in detecting the transducer resonant frequency point.

• That sensor claims to have an analog output so perhaps it would act as a microphone. Not sure...
• You may be better off using a regular 40 kHz transducer as-a-sensor. Its frequency response should be easy to get and it should operate as a microphone.

For levitation at this power, you may have quite a challenge keeping the target stable. And the frequencies and power of multiple transducers may constitute a huge hazard for people or animals in proximity.

• Be sure you know the risks and hazards and take appropriate safety steps before throwing the ON switch.
• Those transducers may not work well in air. Call mfg. and seek guidance and extra datasheets, application notes, etc. Your power Amp may need to run much lower than 60W. IDK.

fwiw