My first ugly DIY system simply used 1/2" PVC ball valves connected to the pressure pump outlet as a "manifold". I think Bill Cody can help you out with a quality liquid filled pressure gauge and even a pressure pop-off valve.
As for a filter, I used 18 gauge steel plate 5/16"x1/4" mnpt hose nipple, 1/4" all thread, a wing nut and 2 nuts and an automotive air filter. I used the plate to make a base and top, drilled holes in the center to attach the all thread to clamp them onto a automotive filter and then drilled and tapped a 1/4" pipe thread hole on the inside of the filter, then connected it to the pump intake.....ugly, but never needed a filter change in 5+years of use.
