A deer has to loose one ounce per pound to become unconscious and die. It all doesn't have to hit the ground... just lost from the blood system. So, 100 pound deer needs to loose about 3 quarts. A 200 pound deer... 6 quarts. You know how much there is in a chest cavity when you field dress them. There really doesn't have to be a lot on the ground to have a very dead deer.

That's the answer to your first question. The second part. If you followed that deer all that distance and didn't find a bed there's no way he's going to die from blood loss. He may die from infection or something like that... but not from blood loss. Sounds like a very superficial wound as far as a deer goes. They're tough critters. I'm surprised you kept finding drops of blood. He must be on blood thinners or something. Usually they clot up after a while. Must be right on a big working muscle he has to use with every step... but since he didn't bed I don't think it's terribly serious.