I'm very, very new, in fact, I'm a moron when it comes to camping, campers, etc. I've been camping many times with friends and love it, but never have owned one. My friend has offered me her camper ...
A trailer sitting unused for a long period is probably going to need new tires, the brakes checked and axles lubed, in addition to assessing any water leak or structural damage. I would either get a friend who is RV savvy or a RV service person to assess the trailer. Then you can make an informed decision.