Hi, Jaxie, I think you've made some thought-provoking comments.
The "Listen carefully" certainly could lead you to believe that the message was meant to be conveyed telephonically rather than by written communication. I think that's something for us all to mull over. I won't say anything more about that until I've mulled it over, except for this one little comment: the kidnapper may have been planning to phone in all or some of those instructions and threats, and something happened to cause him to switch to Plan B--leave a note instead.
Concerning evidence of the writer's knowledge of the death of JonBenet: That's something I searched for with a fine-toothed comb, again and again and again. I'm not convinced of that, but there certainly is a lot of talk about death in the note. All that death talk might have been included to scare the wits out of the Ramseys; incline them toward complying with the kidnappers' demands. In my view it was excessive, but that doesn't help us to identify the author. I think the "At this time" comment comes as close as anything in the note to suggesting knowledge of her death. But, even that isn't proof positive. I recall that in the Lindbergh notes, the writer assured the parents that the baby was well and being properly cared for. How could the parents have known this was a lie? The "experts" of the day were unable to advise them of that. In my opinion, it isn't necessary to be truthful in all particulars in an authentic ransom note; all that's necessary is to convey the idea that the loved one (or person of value) has been abducted and the abductor wants money, else he'll not set him/her free, and may even kill him/her. This is standard kidnapping procedure, as you know.
Some more thoughts that you've provoked: If the plan of the perpetrator were to make the body vanish, per the note, there would be no need to stage any injury to it whatever. Of course, in this scenario, the girl, being dead, had already been injured. If it had been the case that she'd been strangled (ostensibly executed), then, threatening to execute her if the demands weren't met, would be consistent with her evident strangulation. But, threatening to behead her, wasn't consistent with any of her injuries, except in a very remote way--she had been banged in the head. You might consider the cranial injury a form of execution. It wasn't visible but was discovered during autopsy. And, any means of killing would satisfy the threat that she'd die.
New paragraph: If, for some reason, the plan to make the body vanish couldn't be put into effect, and it was decided at length to keep the body in the house; e.g., in the wine cellar, then some staging to provide false evidence of an abduction attempt might be warranted, considering that eventually--sooner or later--the body would be found on the premises. In keeping with the abduction explanation, the Plan A note could be retained as a staging element, providing the wine cellar staging (in this instance) would reflect a botched abduction. Needless to say, selling a botched abduction, with the abductee left dead in the house, would require superior salesmanship. It would make sense that in retaining the ransom note as an element of Plan B, the body wouldn't likely be left in plain view. Who could be convinced that the would-be abductor would fail to retrieve his note, having left the body behind in a conspicuous location?
Unfortunately, for staging theorists, in my view, the wine cellar scene isn't any where near sufficiently evocative of abduction. For one thing, no self-respecting kidnapper strangles his abductee to death prior to departing the premises. Further, the kidnapper doesn't poke his abductee in the vagina with a stick, that he has fashioned from a broken paintbrush, prior to fleeing the scene. Finally, the abductor doesn't apply tape over bloody mucous on the mouth of the abductee; tie her up in such a way that she is hardly restrained, and wrap her papoose-like in her white blanket (the one to which the gown clung when they were removed from the dryer).
The one thing most suggestive of abduction with the intent to collect ransom was absent; namely, properly binding and gagging the abductee. One puny 5-inch strip of duct tape does not a gag make. I say again, it's hard to imagine that anyone decided that strangling the girl and leaving the exotic ligature in place, and injuring her vagina, and depositing her body in the basement storage room, would convince anyone that she'd been killed in an abduction attempt.
Thanks for your fine contribution....
