Please listen to the owner of a 40+yo coach and a member of a large association of such beasties....
All the rubber parts are shot.
That is hose - all, fuel coolant brake and any other you can find.
The fact that the brake fluid and antifreeze have gone bed will not matter as you will loose them when change the related hoses. A brake hose can go bad so it acts like a check valve and does not left the pressure off a caliper. This happens often with old hoses.
Get the flat spotted tire trued and use it as a spare. Make a plan to roll out tires so you don't have to buy a whole set at once - again.
If the wheels are 16.5, start hunting up 16s that fit.
Enjoy your coach, there is nothing there that you can't fix.
Start a log of service and repairs. You will be surprised what you forget.
Matt