John, I really like the way you describe how you will view coach ownership as a relationship.
My first reaction is to avoid moving hastily. As long as you are not pressured to get the coach home immediately start your new relationship with a very careful inspection to determine what works, what doesn’t, what has no impact on the drive home and what has the potential to be a safety issue relating to driving.
Obviously getting it running and insuring all fluid levels, belts, hoses, etc. are OK is important. Make sure house and chassis and possibly generator batteries are strong and healthy because the might prove very important if you have an issue on the way home.
But do not drive it if it will not come up to the driving height and remain there without the engine driven compressor running continuously. A fully functioning air system is important for braking and there are far too many reasons to list here that may contribute or cause the problem you describe. If you can access the underside of the coach safely and with the chassis fully supported at the chassis support points you can get a strong indication of the potential scope of the problem by draining the air tanks in sequence. Pray they are dry and that each in succession is holding air. If water comes out of them the problem ramps up significantly and if it comes out of the accessory tank your likely fix gets more extensive and complicated.
Ask questions here. You can be walked through a lot of situations and we have a considerable number of very qualified Vantare owners to help you.