I don’t know if these are your takes on the author’s ideas, your own, or some combination, but they are very misleading if not outright wrong.
“Cheaper” is hardly the correct word. As you said, the reason was more logistical than anything else.
In any case, by 1941, extermination of the Jews had become an ideological must in the minds of those who called the shots, primarily Himmler and, as you said, by Heydrich. However, it is absolutely untenable to postulate that Hitler had essentially washed his hands of it and let Himmler take charge of the “Jewish question”. For one, that is the opposite of the way things worked in Nazi Germany - Hitler had absolute power. He would delegate, of course, but only to do what he wanted or to achieve his goals. Equally, there was no way that Himmler or anyone else would commit the enormous resources required to exterminate the Jews without Hitler’s support. This is especially true during “Total War” when resources are marshalled for one and only one cause: victory.
It is true that by the fall of 1943, the ‘Operation Reinhard’ camps (built and operated for the express purpose of the extermination of the Polish Jews) were being closed down. In part that was because there were no longer enough Polish Jews around to justify keeping the camps open. But, in larger part, it was because Auschwitz would be more than able to handle any ongoing or future extermination needs (and not because of any ideological shift towards lenience to the Jews).
Well, if by Nazis you mean Himmler, you are right. And, indeed, Himmler tried to ransom several thousand Jews. Eichmann and others, though, did what they could to ensure that as many of the rest of the Jews in the occupied territories continued to be deported to Auschwitz and other camps (both ‘concentration’ and ‘labour’).
Answered above. I will ask again, though, whether you really think it’s possible, that in Hitler’s Nazi Germany, the huge undertaking that would ultimately be known as ‘The Holocaust’ could have taken place without his approval and knowledge? Sure, he may not have known the various details (or maybe he did), but he must have known about the big picture. For goodness sake, the citizens of towns near concentration camps were held accountable (in some sense) for not knowing, or wanting to know, what was going on down the road. Yet Hitler gets a pass?