They used U.S. supplied Stinger missles. Stingers are heat seeking. They home in on infrared.
Of course they were insurgents.
Mostly Soviet supplied radar guided SA-2 SAM missles. But we also lost some B-52s to MiG fighters and AAA flak guns (I believe Jane Fonda was photographed with one of these).
No, of course not. They were regular soldiers serving the established government of North Vietnam. They wore uniforms and bore arms openly. In no way were they "insurgents". Hanoi was defended by the NVA, not the VC.
I believe the US Blackhawks were downed with RPGs.
Debatable. Insurgents fight to overthrow an established goverment, of which Somolia had none.