While I do not remember all specific authors, page numbers and resources as I have read many over the years,
1. I never knew in specifics what killed Joseph. I knew it had something to do with the Turkish conflict.
2. I did not know Kaunitz was deaf by this point. Being in his late 70's in 1788 to 1790 this makes sense. In all of my reading of the reversal of alliances in Europe after 1748 forward through the reigns of Joseph and Leopold, there have been numerous references to Kaunitz and his phobias.
3. Joseph was truly horrified to learn, on his deathbed, his beloved daughter in law died in childbirth. He knew she had given birth and had wanted details. I believe when he found out he said something to the effect of "throw her on top of me."
4. It is good to learn several of the possible reasons why Leopold may have been delayed in coming to Vienna. However, I recall reading Joseph very much wanted Leopold there and was practically begging him to come. My final conclusion is, not discounting the reasons I have learned by what you have shared, Leopold must have, in the end, decided he was simply going to wait until Joseph had died. I had not known Marie Christine and Ferdinand were already working with Leopold to make changes to Joseph's reforms. I do not know enough about Ferdinand's character, but I do believe this, especially when it comes to Marie Christine. (I have not seen any quotes from the letters or correspondences between the 3 of them during the months before Joseph's death.) Besides, Joseph rescinded many of his reforms himself only a short time before he died. I had thought his decision to do this was the apparent unrest of his subjects in his lands and the fact they could not understand what he was trying to do for them. I hope for his sake he did not know what his 3 siblings were doing. Joseph may have been trying to bring his family together before he died, and look at what these 3 were doing! Here is a quote from Marcia Davenport's biography on Mozart (dedicated to her friend Arturo Toscanini) when Joseph died. " Joseph's successor was his brother, Leopold II, a stupid, narrow weakling, who neither knew or cared anything about music. As might be expected of such a small man, his one idea was to assert his new authority in any way that disrupt the routine of his older and greater brother." (Page 336) I do not think Davenport was referring only to music. It is this author's opinion.
5. I believe Joseph, although very preoccupied about problems such as what was happening in Belgium and Hungary, must have been concerned about Marie Antoinette. No, the situation was not yet what it became by 1791 when the remaining royal family tried to flee, (a terrible disaster) but it was already very serious. Considering the facts Louis XVI's two brothers and their families had already left (fled) France and Marie Antoinette and her family has been forced from Versailles to Paris in Oct. 1789, making them virtual prisoners in the capital, and emigrees were already starting to arrive in Austria, how could he not.
6. When I first read about Cosi fan tutte it was in Alfred Einstein's "Mozart, His Character, His Work. " In program notes of various productions and several Mozart biographies it states the opera was produced for the court of Emperor Joseph II. Einstein states Joseph himself ordered the production of this new opera from Mozart and da Ponte in the fall of 1789. I believe Joseph saw the opera. Einstein makes it clear Joseph ordered Cosi due to his love of the Marriage of Figaro. I am not saying Beales is not a fine biographer who has not done his research. However, he is stating his opinion that due to his failing health, Joseph did not see (could not have seen) Cosi in January 1790. And, I disagree with his statement. I believe Joseph would have made every effort to see it, and that he did attend either the premiere on January 26, 1790 or a performance shortly afterwards. Also, I never would have written what I did about the irony of Joseph seeing Cosi in my original post if numerous sources I have read over the years had ever stated anything to indicate he had not seen the opera. I welcome being presented with different viewpoints citing "new" resources but this time, as several friends have pointed out to me, it may have been done to possibly try to diminish what I could possibly know and/or what I was trying to share with readers in my previous post.