Thanks for your very detailed steps. Although very old; for future googlers with an headless server this might be important:

I spent hours troubleshooting emulation which hangs at "1 gamepad detected", and couldnt get any further even when pressing buttons. Apparantly there is an bug where emulationstation will start properly, but hangs if there arent any window managers installed... Installing xfwm4 (on the host) fixed this problem

https://github.com/Aloshi/EmulationStation/issues/291