“NOOB” questions about how TC electronics work?

You got most of it right ...

You can't count on the truck alternator doing much more than keeping up with parasitic battery drain.

Most, if not all of your lights are 12 Volts (usually nbr. 921 lamps).
If you are going to be doing more than a little camping "off the grid" you will want to replace the 921s with LEDs.