Here's a suggestion on the orange peel issues. The Finishline 4 gun from DeVilbiss that I uses has a suggested pressure of 23psi. I suspect that is the pressure they needed to get the gun certified for a specific voc. If you increase your pressure, you will get better atomization. Also, make sure, whatever gun you use, use a 1.3 tip. When I shot the silver metalic on the Waco project, I used "26 square" as I have been calling it. That's the pressure at 26 psi and the viscosity at 26-27 seconds. Viscosity with metalic has to be a little different to account for the metal in suspension. The orange peel sets itself up in the first fog coats so shoot very light, no gloss at all. I have also done large wings in three stages. First, I shoot the three fog coats on the wing. Pressure at 26, viscosity at 26, material open about one turn. I shoot three or four fog coats than stop for the day. 24 hours later, I come back and sand with 320 (dry) and red scotch brite (over tapes) to remove any trash, dirt, etc that may have settled in the paint. I blow and clean the paint, than shoot the final fog and the wet coat at 1-15 open on material knob. I do this because by the time I am done with the fog coats, I'm getting tired reaching and I'm not fresh, just me ...... It takes three hours to scuff sand before the second application of paint. I know that isn't great for many due to the labor cost but it works for me, just something to think about. Smaller parts, control surfaces, etc i do in one application. I also mix only enough paint for the fogs and mix fresh for wet coat. I did have an issue on a hot day that toward the 2-1/2 to 3 hour mark the paint wasn't flowing through the filter very well so I mixed new paint. With solid paints, you can use the higher viscosity numbers also. shoot with your viscosity around 23 seconds or even a little higher, 24 is ok. I have found that the viscosity cups lose their accuracy when you get close to 21 seconds and you can wind up with way too much water in the mix and not know it. It really is important to practice first. Make a few wood frames and cover with fabric and practice the entire process. Do two frames; shoot one for mistakes (too close, to fast, cause a run, sag, etc). shoot the second for perfection. The perfect one will make great prepainted patches should you ever kick up a rock. I still do practice panels with paint colors I have not shot before and to show customers difference between clear vs straight top coat.
These are just a few ideas that may help moving from ok to excellent with your paint.
Marty 57