RetroGamerzIn Recalbox press Hotkey + B to open up Retroarch settings and there you should be able to switch to run games in fullscreen.You also have a 16:9 screen resolution you can change to in the settings menu in Emulationstation but I dont remember exactly where it is and I can not take a look at it because my pi 3 is broken
About the arcade folder in Retropie I dont know.In Recalbox its easy to change between the different emulators.You can do that in the settings option in Emulationstation I think.I have not used Recalbox for awhile so I dont remember exactly where
Recalbox manual https://github.com/recalbox/re…..l-%28EN%29
Recalbox need special arcade romset versions to work and bios files.More about that here:
https://github.com/recalbox/re…..x-%28EN%29
and here
https://github.com/recalbox/re…..x-%28EN%29
Links to full arcade romsets that works in Recalbox: