Low noise voltage regulation
What would be the best approach to constantly having an 8V low-noise output assuming a potential input voltage swinging between 7V and 12V? My initial guess would be to use a flyback or buck-boost switching transformer


It's a good approach. A buck-boost regulator can be implemented in a small area with a minimum component count (no isolation).


  both fixed-output and variable-output regulators both require external components (diode, capacitor, inductor). Why do both require external components?


The reason is that components such as capacitors and inductors occupy too much volume when they are integrated into an IC. For this reason, they are left as external components.