Do you use a 12 volt inverter?

Using the inverter involves a power conversion loss - remember the inverter itself uses power to run, apart from any other consideration. We use a 1 000 W inverter / 12 volt system with two 100 AH batteries. (Old ones). I only use inverter when I need 220V AC, otherwise always 12v.

Is a 10.5 V IIRC a good setting for a Prado fridge?

After trial and error we set up ours to the 10.5v preset (iirc) as the prado voltage often drops to 11v during driving and thus the 11.5 and 12 v preset wasnt letting the fridge run to maintain its coolness. I think your setup should be fine, however, I've got a TX model, so there's far less electronics.

Should I use an inverter or a 12 V plug?

Would it be better to rather use the inverter plug than the 12 v plug. If the car is running, little difference. If it is not, then you will be wasting power. An inverter carries a lower efficiency rating, so you lose around 15-20% by converting to AC. Canon 5DMkIV with L-goodies.

How much power does a 240V inverter take?

The power supply for the fridge when running on 240V would only be about 75% efficient therefore it would be taking about 3.75A form the inverter. The inverter is again proberly about 75% efficient so the inverter would be pulling around 4.7A from the battery when it's running. Not very efficent!

How much power does a 12V fridge use?

happily will the light duty cable running to it where if you were to try and run the fridge on 12V using the same cabling it most likely wouldn't start. Now the down side, we'll assume the fridge uses about 3A (36Watts at 12V) when running. The power supply for the fridge when running