Too many fps games release with half or no controller support. Does this have full plug and play for at least xbone controllers?

Yes

Yes it does, though personally I've had problems binding certain buttons like the stick buttons, but other than that it works perfectly fine.

Is the controller support new?

I have somewhere in tha basement the retail copie for Chasm

and never noticed a controler options on my PC in the days, when I played it.

The game had controller support even back then :-)

Absolutely, tried it withx a genuine XBox360 wired controller, an 8bitdo Pro2 in Bluetooth, 8bitDo Ultimate in 2.4G and a Dualshock 4 through DS4Windows and it works everytime.