You would not need to replace the calipers or brake pads. Just bleed out the brake fluid every 6-7 years and use only Ford Motorhome brake fluid, for the 22,000 pound GVWR chassis or higher rating. It has the lowest 'wet' boiling point of any commercial brake fluid.
Hoses and belts? I replaced mine at around 45,000 miles and 10 years old. No need to worry much about those either for now.
Yes you might want to change the transmission fluid, and give it a new oil change for the engine as well.
Sanitize the water system with a couple of tablespoons of bleach (unscented) and fill the tank with water, then drive around the block to slosh it around, then pump it out the lines, letting the water sit for a hour, then overnight in the lines (after getting in fresh bleached water to the lines).
It should be a great buy.
Fred.