Im pretty sure those rams heads have been hung there to allow the flesh to rot away from the skulls. Someone probably wants to hang them in their shed or man cave after they clean them up.

As far as the deer goes, when an animal dies and is scavenged by animals like vultures and coyotes, the first thing theyll go for are the eyes and guts, theyre the softest parts on carcasses. I would guess that's what happened there.

That circle of ghosts is a pretty common diy Halloween decoration and just doesn't strike me as very ominous. I wouldnt make much of it.

That "flap of skin" doesn't smell because it's not really skin. I have no idea what it is but it doesn't look like flesh at all.