Alsatian, from what you describe I doubt that it was black bear around your tent for a couple of reasons. 1) black bears aren't very good at catching full sized deer, fawns yes, but by the time elk season rolls around, those fawns aren't easy game for black bear. 2) onthe other hand, a black bear has a hard time passing up an easy meal, and if it thinks that easy meal is in a plastic bag or back pack, then you can kill the pack and or bag good bye, because they'll rip'em to shreads if they even smell evidence of a meal.
The blood smear, don't know. A broken blister don't usually bleed that much.
As for what ate just bit of the granola bar, mice!! We deal with them every year if you leave anything out, they will find it.