There is not, and never has been a Cessna called 'Mustang'
how much fuel does a 406 Cessna take
56 US gallons I have a model 172K 1969 manufacture Cessna Skyhawk. It has 38 Gallons usable and 4 gallons unusable therefore the fuel total it will hold is 38+4=42 Gallons. The 56 Gallon answer isn't clear about which model it is and they do vary by model.
20.3 gallons
Depends on the model but the smaller Cessna 150's hold around 25 gallons and the larger Cessna 182 can hold up to 90 gallons.
The Cessna 406, also known as the Cessna Caravan, has a fuel capacity of approximately 110 gallons (416 liters) in its standard configuration. This capacity allows for extended flight ranges, making it suitable for various missions, including cargo transport and passenger flights. The specific fuel capacity can vary slightly depending on the model and modifications.
There are many different kinds of Cessna so your question is un-answerable.
800 pounds
It depends on which Cessna you have, whether you have added auxiliary fuel tanks to it, and how much cargo and pax you are carrying.
You need to state a model number for an exact answer. There are many different Cessnas
They use about 8 gallons per hour in cruise flight.
Cessna 172s hold 56 gallons of fuel. At Felts Field in Spokane, 100LL aviation gasoline is $6.27 per gallon as I write, so it would cost $351.12 to take the plane from completely empty tanks to completely full ones.