trial and error is your best answer as far as needing valves, providing you're only talking a height difference of 2 feet I dont think there will be a problem. the advertised max number of nozzels is 6 due to the pressure drop of each additional nozzle. as far as the tubing, if it has the same dimensions (id, od) and is the same material, color or source has no difference. I would stick with black or another color that blocks light to help reduce the possibility of algae in the lines.