I think she was fed pineapple by the kidnapper(s). Patsy denied feeding her anything. Possibly she snuck down and rummaged it out of the fridge herself.
I think the kidnapper(s) were in the house when they came home, hiding and having already written the ransom note while waiting.
I think the kidnapper (or one of them) knew or knew of the Ramseys, had researched and chosen them for reasons not necesarily obvious to most. It may have been about ransom or perhaps the kidnapper(s) had rationalized it to themselves as a ransom kidnapping, but could not control their perverse desires. Perhaps the ransom was intended to be a ruse and never a seriously intended ransom note.
One thing for sure, the ransom note created quite a diversion and a lot bunny trails as investigators concentrated on it.
I'm starting to think you're right. After thinking about the lack of blood in the house, the strangulation first, and the possibility that the girl came downstairs to get some pineapple out of the fridge, it hit me that she may have encountered an intruder who had been hiding in the basement the whole time and who had written the ransom note while they were at the Christmas party.
My brother suggested that Patsy may have been drunk that night and that is why she was wearing the same clothes the next day. As far as the fibers from a jacket "remarkably like" the one she was wearing found in the ligature, it may simply be that the rope was taken from the house that had prior contact with that jacket.
In any case, the forensic evidence seems to point more to an intruder than to anything done by someone in the home (or supposed to be in the home) since the asphyxiation happened first and there is no blood in the house.
The nature of the asphyxiation is such that it seems that a 9 year old would have a hard time fashioning a ligature like that, twisting it with that much stength and then bashing her head in with that much force (the only thing that would allow it is a baseball bat - but it too would have had traces of blood or bleach on it). No, this was an adult male; methinks now. We'll see.