Carcassonne is a busy regional airport as this is a very popular tourist destination and is served by a number of European airlines. The arrival formalities are straightforward but it is essential to take your pilot's licence and passport etc with you when you leave the aircraft as you will need these to get re-entry airside when returning to the aircraft. The parking lot for GA is some distance from the terminal so it is a good idea to collect all your baggage in one attempt. They will not let you park on the grass but the hard standing does have points for tying down.
We stayed at the ETAP which was a mistake as it was a considerable distance from the main city centre, although not far from the airport, on a soulless industrial estate. I suspect that hotels in Carcassonne will be heavily booked in the main season so it might be an idea to book the Etap as a fallback and try and arrange something else on arrival, whereupon the Etap can be cancelled without charge (before 1800 on day of arrival).
The city is spectacular and needs no introduction. In the old walled part there are many bars and restaurants and a few hotels as well which might be worth sounding out beforehand as this would be a fantastic place for lodgings. As it was, we had a struggle getting a taxi back to the Etap, not helped by the huge thunderstorm going on all around us.
The airport has the usual facilities. We escaped paying any landing or parking charges as we left before that office opened and our attempts to pay elsewhere were met with gallic shrugs. A figure of EUR 24 was mentioned, still low by UK standards for a comparable destination.