Like a window perhaps?
You make a really good point about the gifts. They had just gotten mountains of presents.
http://http://ecx.images-amazon.com/images/I/51kjlKrq-WL._SX382_BO1,204,203,200_.jpg
This is a small picture but it's the only copy of it I can find. It's the cover of a book Lou Smit contributed to. Look at all those toys! A (blue*) bike, a nintendo! What else could they be looking for?
I strongly suspect that the "special visit from santa" was in reference to Charlevoix where they would open gifts with the rest of the family.
The children woke up early. Around 6am IIRC, maybe a little later but still early morning. That's a long day for these kids! You would think they would be too tired to explore and snoop.
Kolar thinks whatever happened started in the breakfast room. Maybe you're right. I think that makes more sense than getting up after they were already in bed. Kolar also believes that the cord was intentional, not staging.
I always leave this forum with even more questions than I had before! This is why we keep coming back I suppose.
*Can someone who has Death of Innocence tell me: didn't they say her bike was pink? It's obviously a minor detail, but I think it would further evidence how they twist the details to fit a story.