You need to decide if you are going to use the stock fuel pressure regulator for the fuel injector fuel supply side or an aftermarket type regulator. If you are going to use an aftermarket regulator, then you need a way to return fuel to the tank (another line/fitting).
For the nitrous system fuel solenoid supply, again you need to decide if you're going to use a dead-headed regulator or a return type regulator. You will need a seperate fuel pump and regulator for the nitrous side, as well as a supply line/fitting for a dead-headed regulator or supply and return lines/fittings for a return type regulator set up.
For example, an external return type regulator and fuel pump for the injector fuel supply side and another external return type regulator and fuel pump for the nitrous side fuel supply will need a total of 4 lines/fittings to/from the fuel tank... 1 supply for the fuel injectors, 1 supply for the nitrous system fuel solenoid, 1 return for the fuel injector regulator return side and 1 return for the nitrous system fuel regulator return side.
If you use the stock fuel regulator you will only need the supply side line/fitting for the inhjectors, and if you use a dead-headed regulator for the nitrous fuel supply you will only need another supply line/fitting for that.
Hopefully this makes sense, it's easy to picture in my mind, but hard to put everything into words.
If anyone has any comments, criticism, clarifications, whatever..... please reply, like everyone I'm always learning.