Disabling Wifi and Bluetooth definitely increases battery life. Not sure about heat. Possibly?
Disable/Enable Wifi
sudo iwconfig wlan0 txpower off
sudo iwconfig wlan0 txpower 15 or sudo iwconfig wlan0 txpower auto ?
Another way:
sudo apt-get install rfkill
# list status of bluetooth and wifi
sudo rfkill list
sudo rfkill block wifi
sudo rfkill block bluetooth
sudo rfkill unblock block wifi
sudo rfkill unblock bluetooth
Place files in: ~/Retropie/retropiemenu then restart Emulationstation for them to show up. Use all the comands to get them to show up in the gamelist.xml in the folder below.
Add to retropiemenu:
/opt/retropie/configs/all/emulationstation/gamelists/retropie/gamelist.xml