I have seen an angolan registred C172 flying in Luanda, and even doing banner towing! but it seems to be more like a paramilitary aircraft..could it be an air-club embryo after all these years of turmoil?
I don't have much infos about 100LL availability but occasional ferrying piston engines use to stop-over and probably refuel in Luanda, maybe is it on prior notice? or "mobgas" ?
I'll try to know more about this when I'll be back there (next week !)
"Peter PanPan" should know more for sure