Shouldn't worry, use the missing kit as a negotiating tool - at least it has the important aircon. Mine is an import, it was via a specialist importer, doesn't even have the extra documentation that yours has. In fact, it doesn't even mention it is imported anywhere in the service book or V5. never had any probs, it is the exact same car, you shouldn't worry. Stories of cars being marked down as imports in the trade only really affect newer cars and the only justification is that EU cars only had one or two years warranty instead of three. I am sure main dealers like to create a feeling that imports are worth less, purely because it is taking their business, they will be only too happy to service it though.
retrofitting MFA would be a nightmare, besides, it makes your drive far too slowly when MPG is in full view! thats what i find anyway. You may find it doesn't have an alarm?? a cheap retro alarm wpuld also give you remote locking.
Mine is actually exact Uk spec, believe it came from Scandinavia. Based on what you said, sounds a good buy. 1 owner, had the nouse and spent the time to search out a good buy, probably looked after it well too.
You can phone up VW Uk about the VIN, they will tell you if its registered on their computers.