Radio/Stereo Install -- help with wiring

[Warty]

I'm installing a modern pioneer into a 1970 Z. This car had a blaupunkt tapedeck installed in the 80s. It powered up when I got the car, but apparently it needs an amp (and they took out the speakers too, but whatever). 

I've been reading up in the FSM, the forum, and google. It seems pretty straightforward, but I want to ask to make sure about 2 things. 

1. What is going on in this picture? This is the radio harness removed. I checked voltage, and the red/blue is +12V at ACC, 0V when off. Blue is +12 always. Some PO wired these together. Then to a 1A fuse. Then to the radio. I don't have wiring diagram for the blaupunckt, so no idea what it had for options. But why would these be wired together? Any reason I can't separate them? The Pioneer wants a constant power line to the battery to retain memory, and another line so it knows when to turn on. 

2. The car has a newer antenna installed, I'm sure it's automatic. The blaunpunkt had only a ground, the power, and a blue line labeled "antenna" coming out of it. The antenna-marked wire was connected to the 240Z's blue-white wire. The blue/white line I *think* I should hook up to what Pioneer calls the remote control, but which is apparently just what you would use to control an automatic antenna. I'm not good with wiring diagrams (in the FSM, etc.). Or is blue/white instead just the interior illumination, and so I should hook it up to the orange/white (pioneer) wire so the stereo turns on lighting at night? 

I'm having trouble tracing the wires from the antenna, they are bundled together with the pack of wires that runs along the right side of the car and comes out under the right-side of the dash.