Bluetooth controllers work, but you have to make the controllers MAC address trusted on the EmuELEC device by sending a ssh command via a network on a PC.
Popular MAME emulators include MAME32 v0.90 for Windows, Nebula v2.23c for Windows, Kawaks v1.63 for Windows.
The EmuElec/EmulationStation software and game roms/iso's are FREE to download (readily available on the internet) and are included at no charge to you.