Welcome to the forum! A bad tape deck is a common problem. They can be repaired but most people don't. A Reatta had a very good paint job from the factory, including dipping the body in primer, so I don't consider them prone to rusting and they are probably above average in that respect. However, the underside of the car is where you should check closely for rust, especially where the engine cradle mounts to the body. The photo below will explain why.
Here is a list of things to check that might help you. What should I check when buying a Reatta?