It's quite common for there to be fuel/oil residue in the airbox, and if running particularly rich, the airbox can be quite wet. If you ever saw how much fuel "stand-off" is generated by the carbs at high RPM, you'd understand why. A similar effect can be seen here:
Performance Engineering stand-off demo
As for your other problem, it's almost certainly due to a stuck or sticky float needles. I'm terrible for not turning the fuel tap to OFF when I stand my bike up, and I have been lucky to never have had a problem, but really the fuel tap should always be turned off several seconds before shutting the motor off, to lower the fuel level in the float bowls.
If your fuel tap is broken I strongly advise you to replace it, or at least repair it. A few members here have reported being able to drill out the rivets on the tap assembly and replace the O-ring, and then use small screws to reassemble it.
The problem you may face, and may already have encountered, is that neat fuel can possibly damage the crank seals over time.
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Andy.
NSR-WORLD.COM
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