SR3 XX Radio (PTT) System And 12 Volt Tap Pigtails

Hello all.

I am a relatively new owner to an SR3XX. I'm looking to wire in radios using the SW4 steering wheel talk button. I've done a little bit of research and it looks like there should be a pigtail right behind the dash of my vehicle that allows me to tap into this system. I do see a radio power harness with a 4PIN plug. Does anybody know what the pin layout is and or how to tap into this system?

I'm also wondering what the 12 Volt auxiliary pigtails on our vehicles are called so I can wire in other 12 Volt components using that same connector.

Thanks in advance!