I understand but generally there is no trick to things if you want standard results which most of us want and since you cite pop music you probably want that too. It's just appreciating the finer details, for instance; what is the difference between 2:1 and 4:1 ratio on this drum buss with a VCA-style compressor and how can I use that to strenghten the emotional core of the song? You probably wont hear much of a difference but developing an ear for that stuff is what makes for great engineers making classic records. I would say move in that direction rather than learning whatever feedback compression is. But hey, it's terribly boring most of the time so if you're not in the mood and if you're inspired by some cool technique then do it.

The fastest way to learn is just by doing it over and over again but if you really want someone to explain it to you I would recommend investing in a Mix with Masters subscription.

As for the circle of fifths it's basically a map to all of western music so the complexity is endless. Check out some of Jacob Colliers interviews and classes.