On the cheap cutting machines, they will usually only tell you that you need to provide a certain PSI to use their machine (I’d also suggest not using any compressor that has less than 14gpm @ 90psi either, you’ll run out of air really quick). In reality, what they are doing inside the machine is metering that PSI through a certain diameter hole in a valve to give the cutting tip on the torch a specific air flow ratio (usually in units like CFM, exactly what is used in welding). Combining a different model or style of torch with a cheap unit like the Chinese imports will most likely give you undesirable results. That machine will be just fine, but I’d try and get the same model of torch, just in a pen style. Unfortunately I couldn’t find a WSD-60 straight torch on Ebay 🙁
The height control device that you want to research is a Torch Height Controller (often referred to as a THC, no jokes). It’s a voltage divider with a Hall effect sensor that sends a signal to your CNC controller and the controller adjusts the height of the torch on the z-axis accordingly. Unfortunately, even the cheapest THC on Ebay is about $230 and we’d probably have to write an entire library to use it with Marlin. It would have to include things like stopping the auto adjust during curves (readings get funky) and placement holding for punching a hole before starting a cut path. Considering most of us don’t even use endstops or auto-homing, I don’t think it will make enough difference to warrant the expense.