Good advice from Bubblehead - and read Saildog's post. Surface mold can generally be removed with a mild bleach solution, and *could* simply be the result of being left outside untended for a long time. However you are quite correct to treat it as a warning flag; sailboats don't like being left outside untended.
Final thought - the boat looks a reasonable length - once you have given it a look over to eliminate a clearly bad boat get a survey done. Somebody once said if you can't afford a survey, you can't afford a boat. Even if you know work will be required, a surveyor will be able to tell you what work....