1. You will have ZERO gains UNLESS you need larger injectors. If you're tuned properly now, and the injectors you have are still large enough to supply enough fuel, adding more fuel with larger injectors won't net anything. This is the same thing as people getting a fuel pressure regulator and higher flow fuel rail and fuel pump when they don't need it. If you're getting the right amount of fuel, adding more doesn't help you.

2. You can get short adapter pigtails that will go from the stock (Denso?) connector to the Bosch/Delphi/Tyco-type universal connector that the RC injectors use, if you're worried about modifying the stock engine harness.