RE: 4 cycle lubrication
Fuel doesn't get to the crankcase. It goes directly from the carb into the combustion chamber. The lower end of 4-strokes get their lubrication from blow-by gasses and oil that goes past the piston and ring into the crankcase. That's why they have a vent, to provide an exit for the excess oil. It sounds like a hit or miss method, but it works.
Paul