Like Thunder just posted above here, have the guy connect a fuel pressure test gauge and show you that the fuel pressure is too low. I have never heard of anyone pressurizing the fuel system in a Dakota, but you or your mechanic can check the internal fuel pressure. Have the guy connect his fuel pressure gauge at the fuel rail test port on the driver's side of the engine, right below the throttle body. At idle, the fuel pressure should be between 47 to 52 psi. If not, there is a problem with the fuel pump, but you would know it because the truck would not run right. Have the guy turn off the truck but leave the fuel pressure gauge connected to the test port. If the pressure falls below 30 psi in 5 minutes or less, the fuel pressure regulator is bad.
Another sign of a bad fuel pressure regulator is if it takes longer than normal to start the truick after it sits overnight or even for a few hours. If it cranks over for more than about 3 seconds before the engine starts, you could have a failing pressure regulator. There is a check valve in the regulator that goes bad around 125,000 miles, and when that happens all the fuel bleeds back out of the fuel line as the truck sits, and that's why it takes a longer time to start. The fuel pump and pressure regulator have to re-prime the lines first before it starts. Another sign of the fuel pressure regulator problem is if it won't start right away unless you turn the ignition key to the on/run position and leave it there for 10 or 15 seconds. When you do that it also re-primes the fuel line.
There are fuel lines at the top of the fuel pump assembly but if they were actually leaking fuel you would smell it from outside the truck. If the mechanic guy says you have a leaking fuel line, make him show it to you before you pay him to fix it. Also, the fuel pump "module" is the same thing as the fuel pump. When it is called a module, generally it refers to the fuel pump, the fuel pressure regulator and the fuel gauge sending unit as a whole assembly. Those 3 parts are all together in the fuel pump housing. The fuel pump is mounted in the gas tank, it is removed from the top side of the tank by either removing the fuel tank or removing the bed of the truck to gain access to the fuel pump.
The only part of the fuel pump module that you can replace separately from the fuel pump is the fuel gauge sending unit. But if you are replacing or having the sending unit replaced, it's smart just to replace the pump too, unless the sending unit failed at a very low mileage. The fuel pressure regulator is an internal part of the fuel pump itself. You have to replace the pump assembly to replace the regulator. If you do replace the fuel pump assembly, the new one also includes a new fuel gauge sending unit.
Sounds to me like you still have a leak some where in the evaporative emissions system. The leaks can be hard to find. But it's not a good idea to leave it unrepaired and let the truck run with the check engine light continuously on. You need that light to be working normally so that it will come back on to alert you if any other engine/transmission/emissions problems come up in the future. If it's already still on due to the old P0442 code, it can't tell you about any other problems that might come up later. Maybe ask the mechanic if they can do a smog test on your emissions system. That's where they inject smoke or smog with a machine, it goes into the evap emissions system and where it leaks, the smoke leaks out, showing you where the problem is. It's kind of like putting a flat tire in water to let the air bubbles show you where it is punctured.