radio communications in fighters

Just wondering if anyone here can explain how the radios in modern fighters work. In particular when scanning I’ve noticed that the aircraft select a frequency to talk to a ground intercept radar operator, then they select a “Kill/comment” frequency. The point Im unsure of is, can the aircraft listen in to both channels, or do they switch freqswhen needed. Also if the flight lead wants to tell his wingman to “tighten it up” or “you forgot to put down your gear, dimwit” is this done on the frequency currently tuned eg approach or is there an intra flight frequency or intercom. Also are the latest UHF radios unscannable?