Well, I spent a few hours at the prime spot - 4, the hill - this afternoon. It's an awesome spotting point at exactly the right location - a shiny example for any airport. Well, not shiny - just a big heap of earth with a bench on top, but then that's just what we need. There are shady trees too, which is even better because it is rather hot in these parts right now.
Spots 1 and 4 ARE doable with public transport - the Volanbusz company runs a cheap and fast service from Kobanya-Kispest metro station to Vecses, Ullo and Monor. Get off/on at Telepi/Anna Utca for Spot 4 - it's maybe a 1.5 km walk. Walking haters note that the last couple of hundred metres need to be walked anyway. Also note that the path to the hill branches off to the right - straight ahead brings you to a little knoll that gives you barely enough elevation to shoot landing aircraft over the fence, and I mistook this for the hill at first.
Of course, a car gives more flexibility in getting around between spots, but I don't regret not renting one because the bad news is that regular traffic at BUD
is of little interest to me - it's almost exclusively low cost and mainline European fare (although I saw a Tatarstan Tu-154 yesterday - and one of the Brasilias undergoing maintenance in a hangar). So I guess I'll spend tomorrow afternoon too in the beautiful city that is Budapest, and in a Turkish bath in particular.
Thanks for the help,