explain ELRS and related things like im dumb.

these are my questions:

do you need a separate flight computer when using an ELRS module with pwm like this one?

if the answer above is yes then can i use an esp32?

if the answer is no, how does it work and do i just need to connect power supply, servos, motor, ect.

how does betaflight work? (i have only ever used Arduino ide)

this is a dumb question but can someone explain the channels and stuff.