I hope you got it for a good price. You mentioned that it had been taken care of but the owners have not used it much the last few years. It didn't start so they probably had a hard time making up their minds to sell it and it just sat while they finally realized they were not going to use it. That's not good.
Fix the leak right away, and find out if the water caused other damage.
Did you have the chassis and house inspected? If so you knew the dash air didn't work. That can get expensive but you can live without it as long as the generator and roof ac work.
It sounds like you may have a project rig on your hands. Hope you are OK with that.