I'd advice you to put a new chain on with a rivet type master link. I've used the clip type master link in other bikes (with less power than the big KTM) without problems, but for some reason, the clip type master link never held on my bike, so I just riveted it and forgot about it.
Maybe your chain damaged the clutch slave when it jumped the sprocket? Maybe it damaged your side stand switch wires and that are the starting problems you are having ? It's a shot in the dark, but I'd look into those two things.
SS. '98 BMW F650 / '06 WR250F / '07 KTM 990 Adv