As for your sound problem, which Pi do you have and which version of Retropie?
There's currently an issue after the Linux OS "Raspbian" which Retropie 4.6 is based on changed the mapping of audio devices in the system.
If you have RetroPie 4.6, you can try two workarounds until Emulation Station is updated, but it requires editing two configuration text files:Edit the file /boot/cmdline.txt and add the following line to it: snd-bcm2835.enable_compat_alsa=1.
orChoose RetroPie-Setup in Emulation Station, then audiosettings, and select "Headphone" as audio output. Edit the file /opt/retropie/configs/all/emulationstation/es_settings.cfg and change the "PCM" in the line <string name="AudioDevice" value="PCM" /> to "Headphone".
If neither of those work alone, try them together.