Oil comes from crankcase breather. It's the opening that is nearly dead center of your airbox (in red, below). Vapor comes in, your bike breathes and burns it. Some of the oil vapor becomes liquid.What would cause the oil in the air box?
Should the fuel line have clamps?
Yeah I read about the oil site glass issue and changed it to spec based on volume. Balance the injectors? Do you mean sync the throttle bodies?I doubt the breather hose was kinked so bad it was shut or you would not have oil in the airbox.
I'm seconding with what jrusell wrote in suspecting the previous owner ran the bike with too much oil. There are plenty of threads about how this can happen if people don't follow the oil change instructions and just put in oil till it shows in the viewing window. Common mistake.
Can't tell a thing about the valves with the boroscope photos because the key is the clearance at the cams under the rocker cover.
On the plus side, the kinked oil breather shows the tank was off the bike at some point and it may have been to check the valves.
There are other reasons the tank may've been lifted, including to balance the injectors which is also common.
With the condition of the plugs and air filter, you might question whether the valves were actually checked.