Leuchars is one of the UK's main Air Force fighter jet bases, so it's not really teed up (pardon the pun...) for handling bizjets, but obviously it's so near to St Andrews that it makes sense for the Open.
As an Air Force base, you're going to be low on services, fuel will be available but you're unlikely to get a lav/water service and very unlikely to get catering (without a fair bit of effort with a local hotel). The hire car thing is probably a trip into Dundee I'd imagine.
If money's no object, I'd probably relocate the aircraft to Edinburgh (it's about an hour's drive by the way) where you can get it cleaned, serviced and pick up the catering before positioning over to Leuchars for the departure.