Sounds like the lash adjusters are not sitting square with the cam. If they crooked, it will eat the cam up in a few thousand miles.
I had a similar problem with a 400 HP small block Ford I built. 1 lifter bore wasn't square with the cam lobe, and it would eat the lobe off of the cam.
You need to check to see if the lash adjuster is worn on one side, or offset in the head.
Another thing is weak metal in the cam, but highly unlikely.
You will most likely need to pull the engine if you haven't done so already, and look it over closely. Especially where the adjusters set in the head.
As to your final drive leaking, there is an o-ring that sits in there, and it could have hardened, or cracked, and allowing the grease to leak onto the wheel.
Check the level in the final drive to see if it's overfull, I'm not sure if that would cause it to leak or not. Have the bike sitting on the centerstand, remove the fill plug, and if the level is correct, the oil should be right at the bottom of the threads.