I just did a tap the other week, specifically for the purpose of working out how to turn water on and off at will, so I could fill up both 1/2’s of a kitchen sink without getting any water on the bench.
I found just like that the best spot to put the water into your tap is the last 1/2 inch before the water comes out. as for water coming through the sides? I just scaled the emitter until the water no longer came through the tap. When this reduced the flow rate too much, I just scaled the emitter so it was taller and had more volume but no more width - voila!!! More water, but not in a thicker, slow plume. This lead me to also discover that the amount of flow can be controlled by scaling the emitter, ok, logical enough… I probably could have read it somewhere if I’d looked.
But it’s not real good for turning the tap on and off quickly without reducing flow to a dribble first. You can select the fluid or the emitter, I forget - and there’s a channel called active. if it’s above zero the fluid flows in, if it’s below the fluid doesn’t inflow. simple.
As for the -Z values, that’s just speed in meters per second. Something will be going at 9.8 m/s, 1 second after it started falling - this is one ‘G’. That said, just go with whatever looks best, fluids are always something of a juggling act, I find.
I can mail you the sink-test I did if you want it. Nice modeling too, by the way. Love the tap especially - reminds me very much of 60’s britain for some strange reason.