You betcha they'll eat up a deer carcass. They are opportunists and will eat anything to stay alive. I've even watched them come in and eat corn off the ground down in south Texas. Of course, that ended up being their last meal, LOL!
Not sure, but what I understand a coyote won't go near a deer carcass pile that has been placed there.
Don't know about that but we have had to scare them off a couple times while on a blood trail tracking a deer. Where we are from they are not as spooky as in other states/areas of the country.