I have a rookie question about APU's. Is there ever a need to run an apu while you are enroute, or do apu's charge an extra battery bank and have inverters built in for creature comforts when taking breaks?

And, In the event I was hired and went solo after training, are the majority of trucks equipped with apu's?

Prices being what they are, is anyone in TL running a $134 walmart standup fridge, low watt microwave, foreman grille, coffee pot ?

Or would I need to purchase my own inverter in a truck without an apu ? if so, what is the largest size allowed and installed by a mechanic at a service center that will run a coffee pot and small microwave? I could always plug a coleman cooler into the cig lighter along with the burton to get by but have to have my coffee.