Horn relay and alt regulator experts needed.

[prostreetC-10]

The goal of this post is to KISS (Keep It Simple Sh**head). lol

I have a no frills truck as many of you know. It is delete EVERYTHING. I have two issues to resolve and I want to use factory wiring if possible. First is that I am going to run the one wire alt from my Camaro on my truck. Loved the way it worked. It's not the jumper wire gig but rather an internal reg that doesn't require a certain RPM to start charging. The first pic is a 4 flat plug that I believe went to the alt reg on the core support. The red wire is constant hot and the brown is a keyed hot. The blue and white wire are the same color as the wires on the alt reg plug. Since the one red wire to the alt is hot when the key is off, does this mean I already have the direct link from the alt to the battery and I don't need anything changed on this plug? It seems like it would.

Next is the pic of what look like a relay. Is that the horn relay? I found the green wire to the horn in the engine bay and assumed since this wire is green and same gauge, it must be the horn. If so....what amp is the relay? What I am trying to do is get my electric fuel pump hooked up and could easily use this setup if it is the horn relay and around 15 amps. Would be really clean this way. I am not into extra wires if I can help it and the gauge is more than enough for the pump. Thanks for any help!