#1 Plug the line to the oil pump.
#2 plug the barbed hose fitting bottom left side of carb. It feeds oil from pump to intake. You can plug by leaving a short piece of hose attached and bend it over on itself and keep it that way with a zip tie or wire. I usually pull the hose barb out with a pair of pliers and plug the hole with a short wood screw or machine screw. I put a generous amount of thread locking compound on the threads before installing. The screw should not extend through to the inside of the carb.
#3 I mix 50:1 for at least 15 years now.
The hose barb from the crankcase below the carb should have a hose attached that goes to your fuel pump on the firewall below the ignition coil. This hose provides the impulse to run your fuel pump from pressure changes in the crankcase.