I have put a water shut off valve at the end of my hose since I started...it helps all that back pressure from going all over the place....the ones at Lowe's ( same style ) are longer than the ones at home depot and last way longer....I also carry the Y in case someone is also there working ( like a landscaper ) and needs water...and a 45 for the hard to get to spots...
as far as the water box dripping...you have a pressure regulator that sits on the inside left of your machine....there is a bolt with a jam nut on the top...pressure up the machine....loosen it up and turn it in until the drip stops....it's allowing to much pressure to come in and poping the pressure cap on the water box......also go into Walmart and in the RV section for $20 get a filter and put it inline somewhere before the water enters the regulator....all it takes id just a grain of dirt to screw that thing up............
this one i n the picture is mine...I switched it over to a Watts regulator..theirs was giving me too many headaches...plus I wanted to monitor the pressure...16to 17 is what you are looking for...anything higher than that and it is going to pop the cap.....