I bought a cheap £10 HVLP with a 0.8 needle off flea bay just to base coat guitar, was suprised at the quality. I would be interested in how yours works and with what paint drobbins. I bought mine purely due to the tip size and price.
I have used lph400 iwatas that spray awesome and you can get a cheapie to spray decent it's all in how you set it up the work just like an AB the dial or cap behind the needle works as a stop controlling the amount od paint sprayed.
Yes mines 2 stage trigger, 1st stage air and 2nd is depending on adjustment at the rear the paint flow. You can feel the bite on mine when you reach the 2nd stage which is perfect to keep air on inbetween strokes. On the side is the fan adjustment and bottom is air but haven't adjusted that at all. I banged it upto 40 psi and away went. Great for £10.
40 psi at the comressor or the gun most base coat comes or there is a tech sheet available which usually states the best pressure for your spray gun which is measured with a regulator on the base of the gun while the air is open.