Det. Arndt stated that she could smell the decomposition on her, but we can assume that she had a trained nose to detect that. It is assumed that she died any time before 2 am, so yes there had been many hours to do all that needed to be done.
But there even if so, there is no other evidence at all to believe his involvement in this crime. Unless we think that he wrote it somewhere else and handed it to the "intruder" to take to the scene... another topic to discuss.

But anyway, I think that if the authorities had any reason to suspect him, they would have investigated him a bit longer.
Accidents do not ask for gender, IQ or age. As we live in a house that we warm up with firewood during winter times, we chop wood for that and have taught our son how to do that since he was 7 years old. If a 7 year old is able to chop wood with an axe, I believe he would also be able to hit hard with anything object on another surface. Especially if angry...
I do not believe that she was pushed over or fell down from anywhere because it would have left additional marks on her body to suggest that.
Neither have I, but it does not mean that it could not have happened. After all I am not an expert on that field nor have received any education about it - but there are experts on that field who have said that it is possible. So I tend to believe those who know what they are talking about.
I have a problem with the theory that strangulation came first because that would mean that there was an intent to kill - it was a deliberate act. I do not believe that any of the Ramsey's wanted to kill her. I see no reason nor motive for that. And as there is very little evidence of an intruder - especially an intruder with an intent to kill her - I have very hard time believing that too. Even If I'd believe Fleet or someone else that the family knew came and did it I do not believe that that someone would have come to the house and just strangled her. As I understand you also believe that Fleet was sexually motivated for this crime - why then strangle her to death first rather than fulfill his fantasies? And it makes me question - if someone strangled her first, why was the head bash needed at all? It makes no sense to hit her. If something seems too complicated. it is not the right way. IMO.
I totally agree with you that it is something that would bother me too. But again we have no proof or reasons to be suspicious of any foul play in this case. And if there is no real cause to be concerned, I think of it as something that is probably not relevant to the case.
But if it is not out of the blue bat there was an accident that had happened? And if it was caused by Burke? We do not know about the previous signs because all the records are sealed. To me, it is something to be suspicious of and tells that there is something to hide. Now, if there were signs and the parents chose to ignore them, they were guilty of knowingly putting JB into harms way (just like the GJ indicted).
If they knew that they would be seen guilty, they needed to cover it all up. Plus add the previous SA to the math.
It is all why we are here for. I hope we will see that day come.