Is the frequency fixed on the individual mics?
NO. It is a selectable frequency quad channels system. You can use more than 10 systems together at the same time using the auto scan function. Thus, the handheld mic frequency is not fixed and you will need to sync it with the receiver.
Can I use the wireless system with my laptop or camera or phone? Can I use it with ZOOM?
We do not recommend it, it since it is specially designed for stereo applications. If connect it to a desktop with separate MIC and headphone jack, you can simply use the 6.3mm to 3.5mm adapter included in the package