Regards the wire... there is no tellin'. PO special, looks to be. That connector does look like a KTM fan connector and there should be a thermostatic switch in the radiator or thereabouts. Go with the KTM fan, it is your best choice.
Now here's a mod that might make good use of that wire, Nak. Heated hand grips. I cannot TELL you how many times I've appreciated them on the XR, once on an early morning at Moab after a cold front moved through. I was able to use my MX gloves in comfort while everyone else was whining and frozen. I wired them for High and Low. Off my rewound stator AC aux coil.
But then I tend to love inclement weather riding. Not sure why. My favorite ride ever was at a Rampart Poker Run that almost got cancelled by snow. 20 people showed up instead of 200, and we all had a blast riding through <4" of snow. Grippy, no dust, quiet, beautiful. It was the first time I'd taken the XR there, I had just opened up the intake and tuned it and it rode on rails and felt like a bike half its weight.