Pax-man, you've pretty much summed up what goes on. Ryanair are the main user of the airport and there are a lot of cargo movements as well, mainly 747's beloning to Polar, Cargolux & Air France, although there's probably more that haven't sprung to mind at this moment. The military are around quite a bit as well (watched a Tornado take off on Tuesday there, good to see & hear
), HMS Ganet is on the North Side of the field which operates SAR Sea Kings and there's also a fairly busy GA scene, there are 2 clubs on the south side. Quite a few airlines use Prestwick for circuits when crews are training on a type. And it also acts as a parking spot for rich golfers at certain times of the year! There will be other people that are there daily that will be able to tell you more detailed info than I can. Hope this is of some use to you.