Regarding the joystick list, with duplicates removed, the following are at least mentioned in the config file. How well each one is supported is another matter, but there is support for changing the button mapping for each joystick. I can imagine a nice table with Joystick name, first firmware version supported, USB ID, button mapping, actual working status etc:
8Bitdo SFC30 GamePad
8Bitdo Zero GamePad
Afterglow Wired Controller for Xbox One
DragonRise Inc. Generic USB Joystick
EA Sports PS3 Controller
GameCube {HuiJia USB box}
GameCube {WiseGroup USB box}
GameStop Gamepad
Generic X-Box pad
Goodbetterbest Ltd USB Controller
Gravis GamePad Pro USB
GreenAsia Inc. USB Joystick
HitBox (PS3/PC) Analog Mode
HJC Game GAMEPAD
hori
HORI CO. LTD. FIGHTING STICK 3
HORI CO. LTD. REAL ARCADE Pro.V3
Hori Pad EX Turbo 2
iBuffalo USB 2-axis 8-button Gamepad
InterAct GoPad I-73000 (Fighting Game Layout)
JC-U3613M - DirectInput Mode
Jess Technology USB Game Controller
Logic3 Controller
Logitech Cordless RumblePad 2
Logitech F310 Gamepad (DInput)
Logitech F310 Gamepad (XInput)
Logitech F510 Gamepad (XInput)
Logitech F710 Gamepad (DInput)
Logitech F710 Gamepad (XInput)
Logitech Logitech Dual Action
Logitech Logitech RumblePad 2 USB
Logitech WingMan Cordless RumblePad
Mad Catz C.T.R.L.R
Mad Catz Fightpad SFxT
Mad Catz Wired Xbox 360 Controller
Mad Catz Xbox 360 Controller
Microntek USB Joystick
Microsoft X-Box 360 pad
Microsoft X-Box One pad
Microsoft X-Box One pad v2
Microsoft X-Box pad (Japan)
Microsoft X-Box pad v2 (US)
Moga Pro
NEXT Classic USB Game Controller
Nintendo Wii U Pro Controller
Nintendo Wiimote
OUYA Game Controller
PC Game Controller
PS3 Controller
PS3 Controller (Bluetooth)
Razer Onza Classic Edition
Razer Onza Tournament
Retro Games LTD THEC64 Joystick
Retro Games The64 Joystick Prototype
Retrolink Classic Controller
RetroLink Saturn Classic Controller
RetroUSB.com RetroPad
RetroUSB.com Super RetroPort
Rock Candy Gamepad for PS3
Rock Candy Wired Controller for Xbox One
Saitek Cyborg V.1 Game Pad
Saitek P2900 Wireless Pad
Saitek P880
Saitek PLC Saitek P3200 Rumble Pad
Sony DualShock 4
Sony DualShock 4 BT
Sony DualShock 4 V2
Sony DualShock 4 V2 BT
Sony DualShock 4 Wireless Adaptor
Sony PS2 pad with SmartJoy adapter
Speedlink TORID Wireless Gamepad
SpeedLink XEOX Pro Analog Gamepad pad
Super Joy Box 5 Pro
Thrustmaster 2 in 1 DT
Thrustmaster Dual Analog 4
Thrustmaster Dual Trigger 3-in-1
Thrustmaster Firestorm Dual Power
Thrustmaster Run N Drive Wireless
Thrustmaster Run N Drive Wireless PS3
Tomee SNES USB Controller
Toodles 2008 Chimp PC/PS3
Twin USB PS2 Adapter
USB Gamepad
USB GamepadChris
Valve Streaming Gamepad
VR-BOX
X360 Controller
X360 Wireless Controller
Xbox Gamepad (userspace driver)