The owner's manual should absolutely come with the bike and usually has a dedicated slot in one of the storage compartments. I think you should also expect two key fobs and generally one physical emergency key that's housed within one of the fobs. As for a toolkit, Goldwings typically come with a basic toolkit that fits in a small compartment, often under the passenger seat or in one of the saddlebags. It won't be a comprehensive set, but it should have essentials for minor adjustments.
When you go to check it out, definitely look for signs of drops like scuffs on the mirrors, handlebar ends, engine covers, and exhaust. Check tire condition, and brake fluid color should be light yellow. Make sure all the lights and electronics work, including the navigation and audio system. If the seller allows, request to see a cold start and listen for any unusual noises or difficulty starting. Also, request for service records and check for any recalls that might have been issued for that model year!
If this is overwhelming and since the seller isn't too familiar with bikes, maybe it will help that a trusted mechanic accompanies you when you do all these inspections so there are expert eyes that can guide you!
