Thanks a ton for this info, mpg numbers dude! It will make things a lot easier.To answer your third question, it's just the 3 orange wires to the 3 leads on the 3-phase rectifier in any order, then two leads from the two on the rectifier to the input on the meanwell, and then connect 12V output from your car to the output leads of the meanwell. There's a little adjustable screw on the back of the meanwell to adjust output voltage.
This is the rectifier I bought: https://www.amazon.com/Baomain-Heatsink-Shape-Bridge-Rectifier/dp/B01JKRIPUK/
It has a heat sink built into it and stays cooler than the meanwell itself.
There is also a tiny parasitic drain (100mA IIRC?) from the meanwell when the car is off. To stop this some people use a relay; I'm using a manual kill switch. If it's just temporary you should be fine if you drive the car at least once every few days.