First, welcome to the Forum.
Typing in capitals is not regarded well, it is like yelling. Please, hit the lock key and turn off all caps.
You'll need to find the leaks in the plumbing and fix them. PEX pipe and crimp or Sharkbite fittings are usually used to replace polybutylene pipe.
Roof leaks are usually fixed by applying a sealant or sealant tape. Dicor lap sealant and Eternabond tape are the favored brands of roofing repair materials. Don't use any silicone anywhere on an RV.
Good luck on the repairs, nice gesture for your friend.