1. Yes, if they're are equipped with ADS-B equipment. Without ADS-B they will apper in my flights list, but aren't shown on the Radar-Map.
2. GROUND, if you have clear line of sight.
3. Regarding to 2. yes if their Transponder is already working, which is usually the case if the airframe is taxiing to and from runway. If you have access to Radarbox network, switch it on and have a look by yourself. Well, ofc ourse there must be another user close to EGLL and have sharing data switched on, so you can watch airframes on Ground.
