Thank you for your post. Hre are a few thoughts by way of an answer.
What is your opinion of the following thoughts.:
.1. The illness and death of O'Sensei's father as a major influence in changing his budo(?) journey from a search for maximum martial effectiveness to an expression of his religious beliefs.
PAG. I think you would need to connect the death of his father with the meeting with Onisaburo Deguchi in Ayabe. After the great fire in Shirataki, Ueshiba set about rebuilding, but at some point word reached him of his father's illness and he set out to return to Tanabe. There is evidence that he had already heard about the Omoto religion and so, making a detour to Ayabe was not quite so unexpected as it might appear. However, I do not think you can consider his father's death in isolation from this.
2. An ongoing change in usage and meaning of the words he used, because of the ongoing developement of his religious thoughts, as a source of confusion to his students.
PAG. I think this might be possible if we could date the discourses with any degree of certainty. We can do this to some extent with Deguchi (and with Kisshomaru Ueshiba, after the war), but I think it very difficult to do this with Morihei Ueshiba, partly because of the enormous editing process that has already taken place.