High speed jets are an orifice plug.-----Not adjustable.----Perhaps you can experiment with different jets to compensate for fuel.----And local atmospheric conditions.----If fuel consumption is a major concern ,this is not the motor for your friend.
????-After the pump that hose does not pull air in.------The earlier V-4 models mounted the pump on the carburetor air box.----They needed a third nipple and hose to provide a PRESSURE pulse to the pump.-----These pumps are very reliable and very simple.
I visit 1 yard with many scrap/ not worth fixing boats.------But I know there are many folks who think.---" it is fiberglass , nothing can be wrong "-----Little do they know of the junk wood in them.----Or shoddy work under the floor !
What you are seeing is all normal for that 2 stroke motor.----The hole is put in to drain the casting cavity.----The leaking oil is the oil you mix with the gasoline !!