PCB is a printend circuit board, if you open Any modern piece of tech it will contain PCBs, it are those green or Brown, sometimes blue plates with transistors and other stuff on it.
I don't know about reset buttons, you might have to write a bash script for that, i don't use retropie a lot. You can add a camera if you want, just remember that, for a gui, you Will need to write a python/bash script, since a command line won't be very usable on a console with only 8 buttons.
thanks if i will use teensy will be easy because i will make a button on the tennsy and program it on the teensy or i will make start + select to exit emulation
my gui is emulationstation on raspbian on the start i will make some systems like apps
and if i can i will make pifba system or MEDNAFEN
and if anyone can help me will be good
i will add a mini wireless keyboard and a wi-fi dongle
i don't know bluetooth will be good or no
can i make something makes the wi-fi dongle is off or on i mean a switch
or a switch program
my buttons is the arrows 8 gaming buttons 1234 or xyab - l1 l2 r1 r2 start select
i think no reset button because i will make start + select = exit emulator
i will add a pi cam
and i will post the specs of the console