Although I was referring only to the number of youtube videos of the Sam the Sham song (!), that's a very interesting bit concerning the Spanish versions of the story. Browsing around the Web leads me to ask: was this Senor Vargo considered to be a Hungarian gentleman?
Tolkien most likely got "warg" from Old Norse and Old English. The first had "vargr" meaning both "wolf" and "outlaw"; the second had "wearh",meaning "outlaw" or "outcast" (not wolf,though ). T. A. Shippey asks why Old Norse felt it needed another name for wolf,when it already had a common one,"ulfr". He suggests that Tolkien may have considered the possibility that this could refer to some special sort of wolf,a "demonic" one. Or even a kind of lycanthope. He certainly adopted the old stories about skin changers with Beorn.
I'll look for those Spanish Red stories. It's an interesting subject. I haven't really studied them much for a number of years, since Bruno Bettelheim's Freudian analysis in "The Uses of Enchantment" back in 1976, rebutted by Robert Danton in "The Great Cat Masssacre"(1984).
Concerning the uses of hallucinogens in ancient or "primitive" societies, my impression has been that it was,and is,very restricted,either to a special class,or by being bound up in ritual. I'm not sure there would be many occasions for the "town drunk" sort of character to get hold of enough to go on a bender.
OTOH,there's the Viking "berserker". Where did that come from? The name "Beowulf" means bear. And Hrolf Kraki had a follower whose nickname,"Bjarki" means "Little Bear",and whose parents' names were also words for bear. It's very suggestive,at the least.
