There could be a solution for the input lag issue. At least it improves things a lot with me.
Get the Sharp mod from Juls, copy and paste controller default folder in your game directory. It's actually the same as Shift1 (as far as I know, to confirm). Copy and paste dinput8.dll too.
I have solution for pads (input lag). You have to edit DampeningEnabled="1" string to "0" in vehicleset_pc_custom_pad.xml and reselect controller scheme in game (to custom pad of course). Now setup deadzones and sensitivity and you are good to go no more input lags, tested by me on ps2 dualshock pad
