Welcome!
The empty oil tank is very common on these bikes when they sit for long periods of time. There is a check-valve that prevents the oil from draining back into the dry sump from the tank, but they tend to leak. Over time, the tank is drained into the sump. If you were to fill the tank, then start the bike, the scavenge pump shoves all that oil into an already full tank, and you end up with oil everywhere. (I've never made that mistake.
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The oil on the left side may possibly be from the automatic chain oiler, located in the center of the counter-shaft.
I agree with mrbreeze and MCRider about the ATF/acetone to un-stick the motor. While I've never used it myself, I have read of many successes. Be aware that when the motor does break loose, the mixture will come flying out the plug holes. I don't remember for sure, but I think the distance record is 12 feet or so.