Yes, to your assumption about the whey protein is distributed. When you drink a protein drink, or eat a peice of meat, the amino acids enter the blood stream (after the GI cells have their fill) and is then carried to all parts of the body where blood travels.
The benefit of taking your protein drink before training is that you will get an increase in the blood flow to whatever muscles you are working and thus will icnrease the delivery of amino acids to those muscles.