One thing you should know if you live in a state that you must pass a SMOG then do not change the way things are. A breather box or catch can as Merrill shows above is for a performance engine. You mush have a closed system or you will fail smog. Use of one of the items above will fail your test. Because it is an open system. As for crankcase gunk going into the intake it's not much. An engine can eat a lot of things. I have seen them eat a finger up to the first knuckle and nothing happened. We tore the hole thing down looking for the finger but it was gone. Snowmobiles don't have air cleaners but they do have a closed breather system.
As for the charcoal canister. It is built catch fuel tank vapors and allow them to be vented into the air cleaner to be burned at a cruse. Solid fuel will be returned to the tank. But I have never seen that happen. Because on the tank there is a separator with a check valve to stop fuel from making it's way to the charcoal canister.