Hi AJS007 and welcome.
3 Answers
1 - ADS-B is digital and uses GPS (in aircraft which have the correct equipment) and is being introduced around the world - there are FAQ's and threads on this forum on the subject, including this one:
http://www.airnavsystems.com/forum/index.php?topic=1040.0. It's definitely the future, not the past!
2 - most military aircraft let you know they are up there by broadcasting a Mode-S signal, which includes their unique code to identify the airframe, and usually their squawk and altitude, but they don't broadcast their position, for obvious security reasons, so we can't plot them on a map. RadarBox picks up the signal and will show the aircraft in the reception list, "MyFlights", but will only show them on the map and shere them on the network if they broadcast position - "ADS-B".
3 - as with answer 2, most GA aircraft and helicopters don't have ADS-B, and most don't even have Mode-S yet. In the UK, all official choppers, including air ambulance and police, have Mode-S but not ADS-B. so, again, we know theye're there, but we don't know where.
At the moment, most contacts displayed by RB are civil (and military) airliners, but more and more aircraft are being equipped with ADS-B, so things will only improve with time. RB is a good investment!
Hope that helps.
Rod
Hope that helps