Stock, the bike holds 5.3 qts. When we drain, we can only remove and replace 4.3 qts. One remains in the engine. typically, about 2 qts. goes in, and remains with, both the engine and the tank, since we've learned to change out only 4 qts.
This would seem to mean that 3 to 3.2 qts. would be in the engine, and that you can only change about 2 qts at a time.
The back hose is to equalize pressure between the engine and the tank. It can probably be blocked off okay. The forward one is a true engine breather, and must be allowed to remain open... but, since oil and vapor will pass through that neck, you must put a hose on it, and vent it somehow.
Stock, it went to the air cleaner. For those of us without the stock air cleaner, we run a hose, either down below the engine, or, as I have done, up the frame spine, under the tank, to an auto crankcase breather filter, like the Autozone AF59, for under $3.
Did I get this right, fellas?