They come from RAF Coningsby. If you zoom in you can see the sheds where they kept, south of the runway. Even more interesting if you get a google sat view and zoom in!
nope, i See EF-2000's, Lakenheath F-15C and E's all the time, BAE Hawks, F-16's..... Europe is where you see the most fighters. typically around 2-5 AM Central time since i see them 3-6AM Eastern.
I think Mode 5 is not a thing outside the US. If you want to see fighters, check out the airspace over Belgium (they fly F-16s), southern England (as you might have noticed - EUFIs and F-15s, sometimes also Tornados), Netherlands (they seem to have bought a bunch of F-35s, I spotted one a while ago) or southern Germany for EUFIs out of Manching (near Ingolstadt). Their operation times are usually European daytime (might be very early in the morning in the US... ;-))
There's a belgian F16 over UK now.... landed at brize norton earlier, has just taken off: https://globe.adsbexchange.com/?icao=44f041