Zex wet kit fuel line question

I just installed a zex wet nitrous kit on my 99 GT. I'm spraying a 75 shot for now. The instructions said you could get the fuel a few different ways. I just tapped into the incoming fuel line before the rail with the Tee fitting that was included. They also said if the car was equiped with a schrader valve on the fuel rail, you could use the included adapters to screw right into there. I didn't know what this was so I didn't do it at the time.

First of all, is the schrader valve the thing on the front passenger side of the fuel rail with the black plastic cap on it.

And also, yesterday my car was leaking fuel bad from the incoming fuel line, but not from where I tapped into it. The shiny chrome disc in line with the fuel line was leaking. Where the fuel line went into that disc, gas was spraying out. What is that, and why would it be doing that? I'm thingking about moving my fuel line for the zex kit to the schrader valve and replacing the fuel line that it was tapped into. I think it would just look cleaner. Is that line easy to replace?

Thanks in advance for any help.

Is there a difference in getting the fuel before the fuel rail or from getting it on the fuel rail from the schrader valve? I don't know any pros or cons to this option.
I would do it the way you did with the fuel block but my solenoids are on the other side of the engine bay and I don't want to run it all the way across the engine.